Examples include:
Do not abuse children it is illeage (against the law)
Some people want to deport all illegal immigrants.
He came as an illegal alien and spent several years legalizing his status.
Stealing is illegal.
Murder is illegal.
It is often senseless how people deliberately kill animals even though its illegal.
It is illegal to jump the turnstile.
Illegible means that something which is difficule to read. So the sentence will be "His handwriting is illegible as I can't read what he is trying to say."
Booze was once illegal.
Abduction is highly illegal in the US.
It is illegal to plagiarize work.
Cannibalism should be illegal.