When I worked in a pub many years ago, the miserable landlord was paying an absolute pittance in wages, due to this he was able to go on long holidays 4 or 5 times a year. I ratted him out to the appropriate people, was assured he wouldn't find out it was me, they went along under the pretext of doing an audit of his books, pointed out to him that the wages he was paying wasn't up to the current standard. He was made to pay us all the relevant back pay of several hundred pounds.
My neighbour was assaulted by her husband last week, ending up with two black eyes. I regret not calling the police (someone else did), but if it happens again I will do so.