What Is Moral Turpitude?
Crime involving dishonesty, fraud, or violence. Examples: theft, fraud, rape, assault. Not traffic violations or simple drug possession (sometimes).
Effect on Citizenship
Conviction for crime of moral turpitude within 5 years = citizenship denied. Older convictions considered on case-by-case basis.
What to Do
If you have conviction: consult immigration lawyer before applying. Some convictions can be challenged. Records can sometimes be expunged.