Trademark and Public Domain

[Adam Milfus]

What is the name of your state (only U.S. law)? California

Can I use movie stills from public domain stills for commercial use? Namely sweaters and t-shirts?

For example, can I take a screenshot from a Betty Boop cartoon, which is in public domain, and print that on a piece of clothing for profit?

What if I were to take the screen shot and alter it?

 

[The Occultist]

Trademarks don't really fall into the public domain. As far as your example, Betty Boop is currently owned by King Features Syndicate, and they do defend their trademarks.