It doesn’t seem that clear to me, because from this law firm’s side, you’re wrong. Which is why they’re asking the court.

Public domain means public domain. Anyone should be able to use the image of steamboat Willie for any purpose, because he was copyrighted separately from Mickey Mouse. Copyright isn’t forever, it’s embarrassing that it’s gone on this long.

Provided that the law firm is suing literally to ask the question, it doesn’t seem so easy.

Edited to add: I was curious about rights of celebrities after death, and it turns out Marilyn Monroe is actually a bad example because her estate actually lost that exact lawsuit in 2007 and her likeness has been in the public domain ever since.

California has that kind of post-mortem rights law, and had it at the time, but Monroe’s estate filed estate taxes in New York for years to get discounts… and then claimed California rights when it came to post-mortem publicity rights.

The court found they couldn’t do that, and because New York doesn’t have any of those rights, anyone can (and does) use Marilyn Monroe’s image.

See Shaw Family Archives v. CMG Worldwide for more information.

California’s law for post-mortem publication of likeness is death plus 70 years.

This kind of copyright doesn’t apply to works like Steamboat Willie, a cartoon mouse who can’t die. But if it did, no one would argue Steamboat Willie was still a big thing in 1955, which was 70 years ago.

Sorry this is so long, I just find copyright law fascinating.