Is it legal for someone who has been to prison to become a teacher?

I am attending a community college in Oregon where I signed up for a Peace and Conflict cl. My teacher, Tom H. Hastings, has made it known to the cl that he is an activist and that he has been arrested for protesting before. So, I decided to do some research on him and found that he has been sent to prison for cutting down three support beams at a US thermonuclear navy site. I know that you cannot become a school bus driver if you have been to prison but does that rule apply to college teachers a well?