Even if two works are substantially similar, there may not be infringement if the similarities are only in the uncopyrightable
elements of the work. For example, in the case of Herbert Rosenthal Jewelry
Corp. v. Kalpakian (446 F.2d 738 (9th Cir. 1971)) two jewelers
produced bejeweled pins in the shape of a bee. While the two works were quite
similar to each other, the Court found that there was no infringement.
The Court reasoned that the idea of a bejeweled bee pin was not copyrightable,
only the expression was
The Court found that there
really was no alternative way of making a bejeweled bee pin that wouldn't
be substantially similar to all
other bejeweled bee pins on the market.
Therefore, based on the
doctrine of merger, since there was
no other way to express the uncopyrightable idea, there was no
infringement even though the pins were substantially similar.
The doctrine of merger is that if an idea can only be expressed in
one way or a few ways, granting a copyright on that expression would effectively lock up anybody from using
the idea. Therefore, since
you can't copyright ideas, you can't copyright those limited ways to
express the idea because the idea behind the work merges with its