Last week, the Ninth Circuit Court of Appeals issued an amended opinion in the “Blurred Lines” case. You can read it here. The holding is the same: the jury verdict of copyright infringement is affirmed. But it makes one substantive change to its analysis: it completely ditches mention of the “inverse-ratio rule.”
I blogged extensively about the original opinion previously. As I explained, there are—or ought to be—two kinds of similarity in copyright infringement cases. The first is probative similarity, in which similarity is evidence of copying, along with proof of access to the underlying work. The second is substantial similarity. It goes to whether what was copied is too much of the wrong thing. It is perfectly possible for one work to copy large amounts of the other, and thus very much probatively similar, and yet not be substantially similar. My original blog post has a more detailed explanation.
With respect to probative (but not substantial) similarity, if the two works are nothing alike, then obviously one didn’t copy the other, no matter how much access there was. But if one is a word-by-word, pixel-by-pixel, bit-by-bit, etc. reproduction of the other, then obviously one had to have copied the other, even without proof of access whatsoever. This is a demonstration of the “inverse-ratio rule”: the more probative similarity there is, the less access you need to prove copying; and the more access there is, the less probative similarity you need to prove access.
Alas, courts do not generally make this neat distinction between probative and substantial similarity. Courts tend, instead, to see infringement as access plus substantial similarity, with “substantial similarity” doing double duty as both probative and substantial. As a result, the inverse-ratio rule gets misused sometimes, like this. The more access, the less substantial similarity, and vice versa.
But the Ninth Circuit not only fails to make the distinction: it makes the distinction, then mixes them up. Instead of copying (with its probative similarity) and misappropriation (for lack of a better term, with its substantial similarity), the Ninth Circuit has “external similarity” and “internal similarity.” “External similarity” is objective evidence of similarity—analogous but not the same as probative similarity. “Internal similarity” is the jury’s gut instinct about similarity, and thus analogous but not the same as substantial similarity. Access, however, exists outside of both, and so the inverse-ratio rule is misused the same way as in other courts.
In the original opinion, the Ninth Circuit relied somewhat on the inverse-ratio rule to affirm the jury verdict. The Thicke-Williams parties were caught in a bind: they had to concede access, but access continued to be used against them via the inverse-ratio rule. Since access was conceded, a thumb was placed heavily down on the “substantial similarity”2Which, remember, is really probative and substantial similarity all mixed up. side of the scale, so that even small amounts of similarity would suffice. As I explained, this was unfair to the Thicke-Williams folks.
As it happens, the Ninth Circuit’s foray into the inverse-ratio rule was unnecessary. It was upholding a fairly non-controversial jury instruction that copying need not be intentional or even knowing to constitute infringement. The Thicke-Williams folks tried to use this jury instruction as a vehicle to complain about the unfairness of the continued viability of access even after they conceded it. But that argument was never going to work, because the jury instruction was accurate. True, it could have been clearer about what it meant by “copying,” i.e., not just access, but access plus “substantial similarity.” But other instructions explain what “copying” is, and in the grand scheme of jury instructions—which by and large are terrible—it’s really above average. The worst the Thicke-Williams folks could say about it is that the instruction was unnecessary in light of their admission of access, but even then, they aren’t about to admit “copying” as a whole.
Perhaps recognizing that the inverse-ratio rule is fraught—something pointed out forcefully by the dissent—and unnecessary in this context, the majority did the simple thing: just cut it out its analysis. Having said that, we can perhaps see this as a positive development. The inverse-ratio rule is embarrassing, at least as applied by most courts. And maybe this will encourage courts to tease out what is wrong with it, and to learn about Laureyssens v. Idea Group, and how it correctly divides probative and substantial similarity. There’s cause for hope, since the Ninth Circuit recently cited Laureyssens in the Nike-Jumpman case. Remember, the inverse-ratio rule is not a bad, just drawn that way, er, misapplied. When applied to probative similarity, it works like a charm.
Thanks for reading!


Rick Sanders

Rick is the litigation half of Aaron & Sanders, PLLC; and, from 2012 to 2014, an adjunct professor at Vanderbilt University Law School, where he was teaching Copyright Law. Vandy also happens to be where he got his law degree in 2000. After graduation, he practiced at a major intellectual-property law firm in Silicon Valley for a few years. He returned to Nashville in 2004, where he worked for a large Nashville firm, practicing as much intellectual-property law as he could, but also a lot of commercial law. He left that firm in 2011 to start Aaron & Sanders with Tara Aaron, so he could practice intellectual-property law full time and work with start-ups and other non-institutional clients.