Depends on your state. Most times though lemon laws don't apply to as is. Some dealers may and I use that loosely, may allow a return or they fix whats wrong if its in the 3 days. Most won't and if its a private sale it's not going to happen.
I'm a retired car salesman. Lots of WRONG answers are being given here. Please allow me to correct a couple points: ****** Lemon laws are FEDERAL, not state, regulations that deal with NEW cars only. Not used cars. If your NEW car has a repair issue, you must allow the dealership to correct the issue under the warranty coverage program. If the SAME issue does not resolve within 3 visits & a 1-year period, you can file a claim to the manufacturer for relief under the federal lemon law guidelines. If you bought a NEW car, you'd know this as your salesman would give you a copy of the lemon law papers & explain your rights to you. None of this applies if you bought a USED car.
It actually depends on the coverage of the lemon law in your state, it might or it might not. Better check it or seek the help of a lemon law attorney from http://californialemonlawguide.com/ to be sure. It always pays to know your rights and the laws in your state.