If he hasn't reported the assault to the police in more than two weeks, he's going to have a tough time getting you prosecuted criminally. If he sues you civilly, he's going to have a tough time getting anything like a $5,000 award for a small bruise with no medical treatment. I wouldn't call it extortion, but he is asking you to pay a much higher price for what you did than you're likely to have to pay if you just say no and let him choose his next move. No guarantees, of course. Anything is possible, but based on the facts you've stated, his desired outcome is highly unlikely unless you just give in and pay him the $5,000 he's demanded.
Answered on Oct 10th, 2013 at 12:20 PM