All schools have a written code of conduct that all students and teachers must abide by.
All colleges, to my knowledge, have extremely strict policies about cheating and plagiarism. Those are the two biggies when it comes to academics.
In both cases, expulsion is possible. In some instances, a professor or administrator may choose to weigh the infraction and decide on a less severe punishment, like being put on academic probation. However, in my experience, that is rare. Most schools, to protect their reputation and the reputations of the other students, will opt for expulsion.
There are always exceptions to the rule(s). Some colleges will decide to fail you in that particular class and put you on probation.
I don't know if you are asking this question hypothetically or if this is something that you are dealing with personally. If this has happened to you, then I think it would be better, overall, if you speak to an advisor and tell the truth up front. You may get away with a repeat on that particular text/exam and probation.
Honesty, in academia, can get you very far.