Can "substantial similarity" of expression be the subject of expert testimony? No, says the Eighth Circuit in The Rottlund Co. v. Pinnacle Corp., No. 05-1296 (8th Cir. June 20, 2006).
The case involved allegations that the defendant infringed plaintiff's copyrights in townhouse design plans. In a copyright case, plaintiffs must show ownership of a valid copyright (this was not at issue) and copying of protected expression. Copying of protected expression can be shown by direct evidence of copying OR indirectly by showing (a) access to the copyrighted materials (this was not at issue) and (b) substantial similarity of both (i) ideas (this was not at issue) and (ii) expression. (The three elements that were not at issue were decided in plaintiff's favor at summary judgment.)
So the real issues left for the jury were: was there direct copying; and were the defendants' works substantially similar to the expression in plaintiff's works?
The Eighth Circuit explained that to determine whether there's a substantial similarity of expression, expert opinion and "analytical dissection" (i.e., element-by-element comparison) are impermissible. Instead, substantial similarity of expression is an "intrinsic" issue: it is measured by the response of an ordinary, reasonable person.
The trial court, however, had allowed the defendants to put on an expert who testified regarding what he believed to be key differences between several individual elements of parties' townhouse layouts. He also testified several times that, in his opinion, these differences led him to the conclusion that there was "no copying." The jury apparently believed the expert, and found against the plaintiff.
The Eighth Circuit reversed and remanded for a new trial because the district court not only shouldn't have let the expert analytically dissect the individual elements of expression, but it shouldn't have entertained ANY expert testimony at all on the intrinsic issue of similarity of expression. Because that element depends on the perception of an ordinary, reasonable person, that's something the jury should decide for itself. Further, the Eighth Circuit rejected the defendant's explanation that the expert's testimony was merely rebuttal of some small amount of evidence of direct copying, saying that the expert's testimony was "unhelpful" on the "ultimate issue" of copying.