Easy to say until it impacts you in a bad way:

https://www.nbcnews.com/tech/tech-news/ai-generated-evidence...

> “My wife and I have been together for over 30 years, and she has my voice everywhere,” Schlegel said. “She could easily clone my voice on free or inexpensive software to create a threatening message that sounds like it’s from me and walk into any courthouse around the country with that recording.”

> “The judge will sign that restraining order. They will sign every single time,” said Schlegel, referring to the hypothetical recording. “So you lose your cat, dog, guns, house, you lose everything.”

At the moment, the only alternative is courts simply never accept photo/video/audio as evidence. I know if I were a juror I wouldn't.

At the same time, yeah, watermarks won't work. Sure, Google can add a watermark/fingerprint that is impossible to remove, but there will be tools that won't put such watermarks/fingerprints.

Testimony is evidence. I don't think most cases have any physical evidence.