My wife works over 40 hours per week and receives no overtime. IS her employer breaking the law and if so what should she do?

It really depends on her job/position.  While the general FLSA rule (and most state laws) is that any hours worked over 40 in a week must be compensated at the premium rate of time-and-a-half.  However, there are many exemptions to the law - too many to list.  The most common exemption is if your wife is in a management position or a professional (engineer, architect, etc.)  But because there are so many exemptions and nuances to the exemptions, I suggest you contact a local attorney, especially to deal with any possible state law violations.