A policeman or woman is someone who is the upholder of the law and as such needs to "lead the way". This means acting within the law at all times whether off duty or on. If you are a policeman and can't act within the law then you should resign and do something else.
With regard to the issue of pressure, what pressure is a policeman under that, say, your average individual isn't? We all have our pressures in life, and breaking the law, especially in this way, is no excuse for anything.