I have to know and keep a current CPR license (requirement of Nursing school).
My instructor for the CPR class made a damn good point regarding using CPR on strangers. NEVER obligate yourself to help unless you are comfortable. His example went something like this...
You see a crowd of people at the mall, and someone shouting for help, so you go running up declaring that you know CPR and can help. You have now obligated yourself to help this person, and cannot abandon them. You get closer, and realize it is a bum, who is coughing red crap up and looks like he is has more diseases than humans have cataloged. Don't you wish you had assessed the situation beforehand, and maybe kept your mouth shut? Remember, you have no obligation to help people just because you have this little CPR card, it is something you can do if you wish.
Good points as far as I was concerned. I will not perform CPR unless I know the person I am swapping spit with is clean, or I care enough about them to risk it.
Lawsuits acutally do not worry me, mainly since I would have no problem never becoming involved directly with someone sketchy. I will gladly dial 911 and report it, but no way am I going to endanger myself for a stranger. The first rule of CPR is to make sure you do not become a casualty yourself.