Picture Watermark Law

[xentech]

What are the legal ramifications of putting your website URL watermark on non copyright pictures of random people off the internet? I live in the UK but I'm sure the consequences are similar to that of the US. Could they even prove that you put the watermark there? (images wouldn't be released on the hypothetical website in question)

 

[IronLogik]

all pictures are copyright of the creator, by default, which includes random people off the internet. using them, or modifying them for commercial purposes, only builds a stronger case for damages, should they decide to sue.