Is it legal for a company to not hire someone based on the fact that they take online masters courses part-time? Most of the course work is done on the weekends so it does not interfere with the work week? Should this be taken to Human Resources?

Is it legal for a company to not hire someone based on the fact that they take online masters courses part-time? Most of the course work is done on the weekends so it does not interfere with the work week? Should this be taken to Human Resources?