ON PETITION FOR REHEARING
BIRCH, Circuit Judge:
Pursuant to Federal Rule of Appellate Procedure 40(a), the panel hereby grants the appellees' petition for rehearing, withdraws the previous panel opinion dated December 22, 1995, and substitutes the following opinion:
Appellees-cross-appellants Brian E. Bateman and Charles H. Fricker filed an action in federal court against appellants-cross-appellees Mnemonics, Inc., Harry Thompson, David Katz, Parking Automation Corp., BCS, Inc. ("BCS"), and Robert Brunet (collectively "PAC"). The second amended complaint alleged copyright infringement in Bateman's single board computer operating system ("SBCOS") software (Count I), copyright infringement in Bateman and Fricker's hardware logic diagrams for their computer circuit board (Count II), copyright infringement in the programmable array logic ("PAL") software (Count III), false designation of origin in violation of 15 U.S.C. § 1125(a) (Count IV), common law unfair competition (Count V), and theft of trade secrets (Count VI).
Before addressing the many issues involved in this appeal, it is important to set forth the factual and technical background to this complex case. Both Bateman and Fricker are engineers. Bateman created and developed SBCOS software, and the Register of Copyrights registered his claim of copyright in this software.
Initially, Bateman had a business relationship with BCS and its principal, Robert Brunet,
In 1987, Generex was acquired by PAC, a wholly owned subsidiary of Mnemonics, Inc. Pursuant to the BCS/Generex agreement, BCS began delivering SBCs to PAC. In the spring of 1988, Bateman terminated BCS's right to use his SBCOS software on the SBCs that it was selling.
Days after the May agreement between Guidage and Bateman was signed, it was repudiated by Thompson, president of Mnemonics, PAC's parent company. A new contract was negotiated and signed in June of 1988, under which Bateman and Fricker agreed to design the SBC2, which would meet certain of PAC's technical requirements. Bateman and Fricker delivered the SBC2 to PAC in June of 1988. In addition, in November of 1988, pursuant to the June contract, Fricker delivered to PAC "engineering" for the board; these materials were needed in order for PAC to be able to build SBC2s.
Shortly after delivering the engineering to PAC, Bateman and Fricker realized that they had given PAC their only copy of these materials. Because these materials were needed to manufacture more boards, Bateman and Fricker needed to retrieve them. Fricker received back the engineering materials from PAC, signing a receipt to indicate that PAC had loaned the materials to him; Fricker later returned the materials to PAC. It is these engineering materials that are at issue in Bateman and Fricker's theft of trade secret count against PAC.
By January of 1989, the business relationship between Bateman/Fricker and PAC had deteriorated severely. PAC experienced problems with the SBC2s that were in the field, and the parties disputed the cause of the problems. On January 18, 1989, Bateman and Fricker met with Jack Blalock, the
After Bateman and Fricker denied PAC's request for the source code for the SBCOS and the rights to the SBC2 circuit design, PAC undertook to compose its own operating system that would interoperate with the application program that it (or its predecessor, Generex) had written to be compatible with Bateman's SBCOS. Tom Colvin, Mnemonic's senior engineer, was assigned this task. He disassembled and decompiled a portion of Bateman's SBCOS from a computer chip resident on one of the previously delivered SBC2s.
Shortly after the January contract termination by PAC, Bateman and Fricker filed suit in Florida state court, alleging breach of the June 2, 1988 contract.
II. ISSUES ON APPEAL
On appeal, PAC raises eight issues, and Bateman and Fricker present one issue on cross-appeal. The issues on direct appeal are whether: (1) a jury instruction that limited the "successive filtration" test for copyright infringement to nonliteral similarity was confusing or misleading; (2) the district court should have instructed the jury to filter out the operating system/application program interface; (3) it was plain error to instruct the jury that a "qualitatively" small amount of copying could authorize a finding of copyright infringement; (4) the district court erred in directing a verdict striking PAC's omission of copyright notice defense because it found that one copy was a "relatively small number" under the Copyright Act, as a matter of law; (5) the district court erred in denying PAC's motions for directed verdict and JNOV as to claims of copyright infringement in hardware logic diagrams, where the only evidence of damages was the sale of purely utilitarian circuit boards built from them; (6) the district court erred in denying PAC's motions for directed verdict and JNOV as to damages based on sales of circuit boards where Bateman and Fricker failed to introduce evidence that "translations" of their schematics purportedly used in manufacturing circuit boards contained any protectable expression; (7) the district court should have vacated the jury's award of $120,000 in damages for infringement of the hardware logic diagram's copyright, where there was no evidence that any boards were manufactured after PAC had notice of the copyright claim; and (8) the district court erred in denying PAC's motions for directed verdict and JNOV on the state law trade secret claim. The sole issue on cross-appeal is whether the district court abused its discretion in refusing to award exemplary damages on Bateman and Fricker's trade secret claim of Count VI under Fla.Stat. § 688.004(2), given the evidence that supported the jury verdict in Bateman and Fricker's favor on this count.
A. The Feist Two-Pronged Test for Copyright Infringement
At the outset, we review some applicable basic principles. To establish a claim of copyright infringement, Bateman and Fricker must prove "(1) ownership of a valid copyright, and (2) copying of constituent elements of the work that are original." Feist Publications, Inc. v. Rural Tel. Serv. Co., 499 U.S. 340, 361, 111 S.Ct. 1282, 1296, 113 L.Ed.2d 358 (1991); see also BellSouth Advertising & Publishing Corp. v. Donnelley Info. Publishing, Inc., 999 F.2d 1436, 1440 (11th Cir.1993) (en banc), cert. denied, ___ U.S. ___, 114 S.Ct. 943, 127 L.Ed.2d 232 (1994). To "satisfy Feist's first prong, a plaintiff must prove that the work ... is original and that the plaintiff complied with applicable statutory formalities." Lotus Dev. Corp. v. Borland Int'l, Inc., 49 F.3d 807, 813 (1st Cir.1995), aff'd by an equally divided Court, ___ U.S. ___, 116 S.Ct. 804, 133 L.Ed.2d 610 (1996) (citation omitted). In judicial proceedings, a "certificate of registration made before or within five years after first publication of the work shall constitute prima facie evidence of the validity of the copyright and of the facts stated in the certificate." 17 U.S.C. § 410(c) (1977).
It is Feist's second prong that is a central focus of this case. To prove actionable copying, the plaintiff must first establish, as a factual matter, that the alleged infringer "actually used the copyrighted material to create his own work." Engineering Dynamics, Inc. v. Structural Software, Inc., 26 F.3d 1335, 1340 (5th Cir.1994). Proof of copying may be shown either by direct evidence of the copying or, in the absence of such evidence, "[c]opying as a factual matter typically may be inferred from proof of access to the copyrighted work and `probative similarity'" Id. (citing Plains Cotton Co-op. Ass'n v. Goodpasture Computer Serv., Inc., 807 F.2d 1256, 1260 (5th Cir.), cert. denied, 484 U.S. 821, 108 S.Ct. 80, 98 L.Ed.2d 42 (1987)). Factual proof of copying, however, is only an element in satisfying the second prong of Feist.
For the reasons discussed, we need not consider Feist's first prong. The factual copying aspect of Feist's second prong is not at issue either, because PAC admits that it copied portions of the SBCOS code and the SBC2 logic circuit diagrams during the design and development of the LCCOS and the LCC. Thus, the two matters directly at issue on appeal as to Count I are whether: (1) the copying done by PAC is legally actionable; that is, whether there is "substantial similarity" between the allegedly offending program and the protectable, original elements of the copyrighted works; and (2) the use of any such original elements qualifies as a fair use under 17 U.S.C. § 107.
B. The Jury Instructions
PAC raises three separate issues on appeal concerning the district court's instructions to the jury. "We apply a deferential standard of review to a district court's jury instructions. So long as the instructions accurately reflect the law, the trial judge is given wide discretion as to the style and wording employed in the instructions." United States v. Starke, 62 F.3d 1374, 1380 (11th Cir.1995) (citing McElroy v. Firestone Tire & Rubber Co., 894 F.2d 1504, 1509 (11th Cir.1990)). "On appeal, we examine whether the jury charges, considered as a whole, sufficiently instructed the jury so that the jurors understood the issues and were not misled." Wilkinson v. Carnival Cruise Lines, Inc., 920 F.2d 1560, 1569 (11th Cir.1991) (citations omitted). Under this standard, if the jury charge as a whole correctly instructs the jury, even if it is technically imperfect, no reversible error has been committed. Miller v. Universal City Studios, Inc., 650 F.2d 1365, 1372 (5th Cir.1981). We must reverse an erroneous instruction, however, if we are "left with a substantial and ineradicable doubt as to whether the jury was properly guided in its deliberations." Johnson v. Bryant, 671 F.2d 1276, 1280 (11th Cir.1982) (quoting Miller v. Universal City Studios, Inc., 650 F.2d 1365, 1372 (5th Cir.1981)). Instructing a jury in the application of the law of copyright, which is characterized by often subtle and contradictory distinctions, is indeed a daunting task. Thus, the need for proper guidance is accentuated and heightened in directing a jury in this area of the law, which may be foreign to many jurors, particularly in this rapidly changing technological world. Applying the aforementioned standard of review, we examine seriatim the three issues on appeal relating to the jury instructions.
1. Limiting the "Abstraction-Filtration-Comparison" Test to Nonliteral Similarity
PAC asserts that the district court committed reversible error by instructing the jury to filter out only nonliteral similarities in applying the "abstraction-filtration-comparison" test for substantial similarity that the Second Circuit adopted in Computer Assocs. Int'l v. Altai, Inc., 982 F.2d 693 (2d Cir.1992).
The Second Circuit in Altai summarized its abstraction-filtration-comparison test as follows:
Altai, 982 F.2d at 706. In the case at bar, it is Altai's second step, filtration, that most concerns us. Filtration is used to separate protectable expression from nonprotectable material. It is at this step that the structural components at each level of abstraction are examined "to determine whether their particular inclusion at that level was `idea' or was dictated by considerations of efficiency, so as to be necessarily incidental to that idea; required by factors external to the program itself; or taken from the public domain and hence is nonprotectable expression." Altai, 982 F.2d at 707. It is here that PAC claims that merger, scenes a faire, and other originality challenges to literal copying should be applied.
The district court's instruction limited the filtration analysis to nonliteral similarity, stating that:
Supp. R1-318-92-93. This instruction is a verbatim version of Bateman's proposed instruction on determining substantial similarity under the Nimmer test. At the time that this instruction was offered by Bateman,
We recognize that the Altai test was formulated by the Second Circuit to help "determine the scope of copyright protection that extends to a computer program's nonliteral structure." Altai, 982 F.2d at 703. In fact, other circuit courts disagree on whether its application should be limited to instances of nonliteral copying, or whether it is equally applicable to cases involving literal copying. See Lotus, 49 F.3d at 815 (noting that "[w]hile the Altai test may provide a useful framework for assessing the alleged nonliteral copying of computer code, we find it to be of little help in assessing whether the literal copying of a menu command hierarchy constitutes copyright infringement"). But see Gates Rubber Co. v. Bando Chem. Indus., Ltd., 9 F.3d 823 (10th Cir.1993) (elaborating upon the Altai test and endorsing it as a way of determining whether "menus and sorting criteria" are protectable by copyright).
We see this disagreement between the Lotus and Gates courts as more of a matter of semantics than substance. It is undeniable that the Altai court formulated its test to address nonliteral copying of computer code. Even if the Altai test is limited to nonliteral copying, however, a parallel type of analysis must be undertaken in examining alleged instances of literal copying of computer code or screen displays.
We express no opinion as to whether it is better to consider these challenges to literal copying as part of the filtration step or rather to consider them in a separate, yet parallel, analysis. The important point here is that such an analysis is necessary — it makes little difference which methodology is employed.
2. The Failure to Instruct the Jury on the Legal Consequences of Copying Elements Dictated by Compatibility Requirements
PAC also claims that the district court erred in not instructing the jury on the legal consequences of a finding that certain instances of literal copying of code by PAC were dictated by compatibility and interoperability requirements. The district court gave no instruction on whether the application program/SBCOS interface at issue in this case was a constraint that rendered the interface either unprotectable or subject to a fair use analysis.
PAC proposed an instruction that stated, in part, that "you are to filter out as unprotectable expression portions of the program that the evidence shows were dictated by the interface with the applications code which was an external constraint." R7-216 (Instruction No. 26). Bateman objected to this instruction, noting that he had introduced evidence that PAC's application program could have been rewritten to avoid using the interface commands;
The instruction given by the court is not technically incorrect. It fails, however, to define the important term "compatibility"
In analyzing elements dictated by external factors, the Second Circuit in Altai cited Professor Nimmer for the proposition that "`in many instances it is virtually impossible to write a program to perform particular functions in a specific computing environment without employing standard techniques.'" Altai, 982 F.2d at 709 (quoting 3 Nimmer § 13.03[F], at 13-65). The Altai court further elaborated on this point by noting that programmers are often constrained in their design choices by "extrinsic considerations" including "the mechanical specifications of the computer on which a particular program is intended to run" and "compatibility requirements of other programs with which a program is designed to operate in conjunction." Id. at 709-10 (citing Nimmer, at 13-66-71). The Ninth Circuit has similarly noted that computer programs "contain many logical, structural, and visual display elements that are dictated by ... external factors such as compatibility requirements and industry demands," and that "[i]n some circumstances, even the exact set of commands used by a programmer is deemed functional rather than creative for purposes of copyright." Sega, 977 F.2d at 1524.
The Sega and Altai courts are certainly not alone in noting that external factors such as compatibility may work to deny copyright protection to certain portions of a computer program. See also Engineering Dynamics, 26 F.3d at 1347 n. 12.; Atari, 975 F.2d at 839. Whether the protection is unavailable because these factors render the expression unoriginal, nonexpressive per 17 U.S.C. § 102(b), or whether these factors compel a finding of fair use, copyright estoppel, or misuse, the result is to deny copyright protection to portions of the computer program. Thus, we today join these other circuits in finding that external considerations such as compatibility may negate a finding of infringement.
3. "Qualitatively" or "Quantitatively"
Further, we address PAC's claim that the district court erred in instructing the jury that "[e]ven a qualitatively small amount of copied material which remains unfiltered may be sufficiently important to the operation of Mr. Bateman's operating system program to justify a finding of substantial similarity. For instance, a small portion of a structure or code of a program may nonetheless give it its distinctive features. In such a case, a finding of substantial similarity would be appropriate." Supp. R1-318-93 (emphasis added). There is no dispute among the parties that this instruction should have contained the word "quantitatively," not "qualitatively." It is not clear, however, that the judge misspoke, because the written charges that were with the jury during their deliberations correctly read "quantitatively small amount"; the court reporter may have simply heard or transcribed the word incorrectly. Regardless of what actually happened, PAC admits that it did not object to the instruction when it was given.
"[I]f no objection to the instructions was raised at trial, we only review for plain error." Starke, 62 F.3d at 1380 (citing United States v. Andrews, 850 F.2d 1557, 1559 (11th Cir.1988), cert. denied, 488 U.S. 1032, 109 S.Ct. 842, 102 L.Ed.2d 974 (1989)). Under the plain error standard, an instruction will not be reversed "unless `the charge, considered as a whole, is so clearly erroneous as to result in a likelihood of a grave miscarriage of justice,' or the error `seriously affects the fairness, integrity, or public reputation of judicial proceedings.'" United States v. Pepe, 747 F.2d 632, 675 (11th Cir.1984) (quoting United States v. Thevis, 665 F.2d 616, 645 (5th Cir. Unit B), cert. denied, 456 U.S. 1008, 102 S.Ct. 2300, 73 L.Ed.2d 1303, and cert. denied, 458 U.S. 1109, 102 S.Ct. 3489, 73 L.Ed.2d 1370, and cert. denied, 459 U.S. 825, 103 S.Ct. 57, 74 L.Ed.2d 61 (1982)). Analyzing this alleged misstatement in the oral jury instruction, it is clear to us that it does not constitute plain error.
C. Infringement of the Hardware Logic Diagrams
PAC raises four separate issues on appeal concerning the jury award for Bateman and Fricker for PAC's alleged infringement of the copyrighted hardware logic diagrams (Count II). Given our conclusion regarding the improper jury instructions as to Count I and our resultant order of a new trial, we need not address in detail the issues on appeal as to Count II.
Given this standard, we do not believe that a partial new trial only as to Count I would be proper here. We are convinced that the jury was not properly instructed on Count II, and that the general instructions relative to distinguishing copyrightable subject matter from unprotectable work manifestly
D. The Trade Secret Misappropriation Claim
Although Counts I and II are clearly intertwined, Count VI, a pendent state law trade secret claim, is separate and distinct from Counts I and II, and thus we must fully discuss the issues relevant to it on appeal. PAC contends that the district court erred in denying its motions for directed verdict and JNOV on the trade secret claim. Bateman and Fricker, in their sole issue on cross-appeal, contend that the district court abused its discretion in refusing to award exemplary damages on their trade secret claim pursuant to Fla.Stat. § 688.004(2), given the evidence that supported the jury verdict in Bateman and Fricker's favor on this count.
Our review of the district court's disposition of motions for a directed verdict and JNOV is de novo. Colvin v. Housing Auth. of Sarasota, 71 F.3d 864, 866 (11th Cir.1996) (per curiam). The appellate court employs the same standard utilized by the district court in determining whether to grant the motions — "[w]e review all of the evidence in the light most favorable to, and with all reasonable inferences drawn in favor of, the nonmoving party," and "[i]f the facts and inferences are so strong and overwhelmingly in favor of one party that the court believes that reasonable persons could not arrive at a contrary verdict, the grant of a directed verdict is proper." Walker v. NationsBank of Florida, N.A., 53 F.3d 1548, 1555 (11th Cir.1995) (citation omitted). What is required in order for the motion to be denied is substantial evidence of "such quality and weight that reasonable and fair-minded persons in the exercise of impartial judgment might reach different conclusions." Id. As this court has stated before, however, "a jury question does not exist because of a `mere scintilla of evidence'; rather, `[t]here must be a conflict in substantial evidence to create a jury question.'" Id. (quoting Verbraeken v. Westinghouse Elec. Corp., 881 F.2d 1041, 1045 (11th Cir.1989) (quoting Boeing Co. v. Shipman, 411 F.2d 365, 374-75 (5th Cir. 1969)), cert. dismissed, 493 U.S. 1064, 110 S.Ct. 884, 107 L.Ed.2d 1012 (1990).
In the case at bar, Bateman and Fricker's state law trade secret claim is predicated upon the existence of an implied confidential relationship. Given the backdrop of federal preemption pursuant to section 301 of the Copyright Act, we must carefully review this state law claim to ascertain whether it requires an "extra element" for recovery, for "[a] state law claim is not preempted if the `extra element' changes `the nature of the action so that it is qualitatively different from a copyright infringement claim.'" Altai, 982 F.2d at 716 (quoting Mayer v. Josiah Wedgwood & Sons, Ltd., 601 F.Supp. 1523, 1535 (S.D.N.Y.1985)). As a general matter, state law trade secret statutes have been deemed not to be preempted because the plaintiff must prove the existence and breach of a confidential relationship in order to prevail. As the court in Altai stated, "[t]he defendant's breach of duty is the gravamen of such trade secret claims, and supplies the `extra element' that qualitatively distinguishes such trade secret causes of action from claims for copyright infringement that are based solely upon copying." Id. at 717.
We have no doubt that the Florida trade secret statute at issue satisfies the "extra element" test generally employed by courts in performing copyright preemption analysis. However, we find that the evidence presented by Bateman and Fricker, even viewed in the light most favorable to them, fails to establish the existence of a confidential relationship sufficient to trigger liability.
The district court committed reversible error as to Count I both in improperly instructing the jury to filter out only instances of nonliteral copying in the "substantial similarity" analysis, and in not instructing the jury on the legal consequences of copying dictated by compatibility requirements. Since Count I and Count II are not "so distinct and separable" as to permit a partial new trial on Count I alone, the judgment of the district court is VACATED on Counts I and II, and the case is REMANDED for a new trial on these counts. The judgment of the district court on the trade secret misappropriation count is REVERSED, and the district court is instructed to enter judgment as a matter of law for PAC on the trade secret count.
VACATED IN PART; REVERSED IN PART, and REMANDED.
Timothy S. Teter, Note, Merger and the Machines: An Analysis of the Pro-Compatibility Trend in Computer Software Copyright Cases, 45 Stan. L.Rev. 1061, 1063 (1993) (hereinafter "Teter") (footnotes omitted).
Although operating systems and application programs generally perform separate functions, the distinction between them is not always clear and continues to erode as programs become more advanced. "For example, since Lotus 1-2-3 executes `macros' (user-written command sequences), it can be considered to be a hybrid operating system/application program." Id. at n. 15.
3 Melville B. Nimmer & David Nimmer, Nimmer on Copyright § 13.03[F] n. 271 (1995) (hereinafter "Nimmer"). See also E.F. Johnson Co. v. Uniden Corp. of America, 623 F.Supp. 1485, 1488 (D.Minn.1985) (defining the terms "source code" and "object code").
Since object code is only machine readable, PAC would have had to disassemble and decompile it for it to be of any use. See Robert A. Kreiss, Accessibility and Commercialization in Copyright Theory, 43 UCLA L.Rev. 1, 32 n. 110 (1995) (hereinafter "Kreiss") (noting that "object code, in the vast quantities found in normal computer programs, is not, as a practical matter, humanly accessible to programmers"). "Disassembly," which is a reverse engineering term that includes both disassembly and decompilation, "`is a procedure for translating the machine language program into an assembly language program.'" Kreiss, at 3 n. 8 (quoting Office of Technology Assessment, Finding A Balance: Computer Software, Intellectual Property and the Challenge of Technological Change 146 (1992)). Thus, PAC requested the source code for Bateman's SBCOS, which would have afforded greater insight into the workings and structure of the SBCOS software; in particular, it would have provided PAC with any accompanying programmer notes.
3 Nimmer § 13.03[F] n. 271 (citation omitted).
PAC utilized the techniques of disassembly and decompilation on Bateman's SBCOS. PAC claims that such reverse engineering was necessary to develop an operating system compatible with its application program, which in turn was written to be compatible with Bateman's SBCOS. Although the issue is not directly before us on appeal, it will likely appear on remand, and thus we think it proper to address it and thereby provide some guidance to the district court on remand. See United States v. Costa, 31 F.3d 1073, 1080 (11th Cir.1994). And although there has been some uncertainty as to whether reverse engineering constitutes copyright infringement, the one federal circuit court that has squarely addressed the issue has concluded that reverse engineering may be a fair use. See Sega Enters. Ltd. v. Accolade, Inc., 977 F.2d 1510, 1527-28 (9th Cir.1992) (holding that "where disassembly is the only way to gain access to the ideas and functional elements embodied in a copyrighted computer program and where there is a legitimate reason for seeking such access, disassembly is a fair use of the copyrighted work, as a matter of law"). Another federal circuit court has addressed the issue, although its highly unusual factual posture seems to limit its precedential value. See Atari Games Corp. v. Nintendo of America Inc., 975 F.2d 832, 843 (Fed.Cir.1992) (concluding that "reverse engineering object code to discern the unprotectable ideas in a computer program is a fair use," although denying the defendant's fair use claim, based on the fact that it was wrongfully in possession of the source code). We find the Sega opinion persuasive in view of the principal purpose of copyright — the advancement of science and the arts. See Feist Publications, Inc. v. Rural Tel. Serv. Co., 499 U.S. 340, 348, 111 S.Ct. 1282, 1290, 113 L.Ed.2d 358 (1991) (noting that "[t]he primary objective of copyright is not to reward the labor of authors, but `[t]o promote the Progress of Science and useful Arts'") (quoting U.S. Const. art. I, § 8, cl. 8). We note that we are in good company in endorsing the approach of the Sega court. Eleven copyright law professors filed an amicus curiae brief in the Sega case in which they endorsed this approach. See Kreiss, at 4 n. 9 (citing Brief Amicus Curae [sic] of Eleven Copyright Law Professors in Sega Enterprises Ltd. v. Accolade, Inc., 33 Jurimetrics J. 147, 155 (1992)). For an extensive list of law review articles discussing the Sega and/or Atari cases, see Kreiss, at 61 n. 226. As discussed subsequently in this opinion, an important distinction to be emphasized is that reverse engineering, in addition to accessing nonprotectable ideas and functional elements, may also yield access to original expression. However, while the former may be unoriginal and not worthy of copyright protection, the latter, though original and hence copyrightable, may also be denied protection where its use is found to be "fair" under 17 U.S.C. § 107.
It is in this substantial similarity analysis that one must distinguish between literal and nonliteral similarity. Literal similarity refers to similarity at the code level; that is, there is a verbatim copying of part or all of the source or object codes of a computer program. Nonliteral similarity is more difficult to define. Professor Nimmer refers to it as "comprehensive nonliteral similarity," and notes that the term "similarity" is not limited to a particular line or paragraph of a work, but refers rather to where "the fundamental essence or structure of one work is duplicated in another." Id. at § 13.03[A]. Thus, nonliteral similarity can be thought of as paraphrasing or copying the essence or structure of a work just short of literal copying. Both literal and nonliteral similarity may warrant a finding of copyright infringement, although we note that the application of these theories becomes more difficult as cases assume an increasing technological complexity. In the computer code environment, one may write code that, when processed by the computer, produces a screen display that is virtually identical to another screen display that was generated from unquestionably dissimilar code. See Digital Communications Assocs. v. Softklone Distrib. Corp., 659 F.Supp. 449, 455 (N.D.Ga.1987) (noting that "a computer screen display can be copied by means of a computer program which is not itself a copy of the computer program which generated the screen display which has been copied"). Such an instance would not warrant a finding of literal code copying, but could constitute an infringement of the portion of the screen display that properly qualified for protection.
Teter, at 1064 (emphasis added).
Although the factual situation in this hypothetical is not identical to the case at bar, it is close enough to highlight the importance of the operating system interface.