See, for example, how US Senators pressure payment providers to check up on whether their customers may be profiting from illegal file-sharing:
https://www.leahy.senate.gov/press/judiciary-chair-leahy-urg...
If Dropbox-style hash checking of files could be seen as the standard in the industry, I can see how failing to do that could be seen by a court as potentially negligent.
See, for example, how US Senators pressure payment providers to check up on whether their customers may be profiting from illegal file-sharing:
https://www.leahy.senate.gov/press/judiciary-chair-leahy-urg...
If Dropbox-style hash checking of files could be seen as the standard in the industry, I can see how failing to do that could be seen by a court as potentially negligent.