Alibi

Pronounced "alibai", an alibi is a type of defense found in legal proceedings by demonstrating that the defendant was not in the place where an alleged offense was committed.
It is the same meanings for any other type of defense, it is like a proven excuse to demonstrate that you did not make an action  because you were doing something else.
"The guy in the Shaggy´s song "it wasn't me", has practically no alibi to prove it was not him, he can only run away.