Marc Jacobs has doubts that Kurt Cobain created a smiley face design that is the subject of an ongoing legal fight. On Tuesday, via counterclaims against Nirvana, the fashion designer seeks a declaration that the band’s copyright registration is invalid and unenforceable.

The move comes after a California federal court allowed Nirvana to move forward in a lawsuit alleging that one of Marc Jacobs’ T-shirts infringes the logo. The judge ruled that the complaint sufficiently alleges Nirvana owns the copyright registration and that the design is similar enough to the T-shirt to survive a motion to dismiss. The court also ruled that a chain-of-title challenge was best handled through subsequent proceedings while deferring other fancy defenses including issue of when the smiley face design was actually published.

Since then, attorneys for Marc Jacobs have been dissatisfied with being limited to two depositions to explore the creation of the logo. The defendant deposed David Grohl and Krist Novoselic, the two surviving members of the band, who each testified they didn’t know who created the logo.

In briefing papers, Nirvana lawyers responded that Marc Jacobs was more focused on interviewing celebrity witnesses rather than individuals identified on the copyright registration and assignment documents. Furthermore, they noted that neither Grohl nor Novoselic were asked if they believed Cobain to be the creator, and if so, the basis for such belief.

Seemingly angling for more discovery, Marc Jacobs is playing defense by going on offense with a new counterclaim.

“The apparent absence of any living person with first-hand knowledge of the creation of the allegedly copyrighted work in question, coupled with numerous other deficiencies in the 166 Registration that is the basis for Nirvana’s infringement claim are the basis for the counterclaim asserted,” states the court papers.

Kurt Cobain is obviously dead and can’t testify, and the copyright registration enjoys some presumption of validity. How much so — and which side has the burden of proof — appears to be where the case is headed next.

This article originally appeared on the Hollywood Reporter.