I live in Michigan and in December I submitted a request for 1 week vacation time to be taken in March (as I was getting married) and the time off request was approved. In February I ended up having an elective surgery procedure and I used all of my vacation and sick time. I was willing to take my 1 week vacation unpaid as I was getting married but my employer then denied my previously approved time off stating "we simply do not allow employees to take time they do not have." Prior to them denying my non-FMLA leave, my direct supervisor asked me for details such as the exact dates I would be out of town, the date I was getting married, etc stating that he would use that info to support my request but if they just do not allow employees to take time they do not have, why would he have needed that info? Their reasoning simply is not true. Other employees have taken non-FMLA leave of absences so they do allow employees to take time they do not have. Can I sue them for this? I had to cancel a life changing event and instead of having my destination wedding I had to go down to the court house and get married.

You absolutely cannot sue them as they are doing nothing wrong.

If its workplace policy to not allow time off that you don't have, it's pretty black and white. It sounds to me that your supervisor was willing to plead your case if you supplied him with the information he was asking for. It also seems that "rules can be broken" which is why he asked for details to plead your case for you.

In my experience, employees opting for "elective" surgery causes tension and your timing was unfortunate. We've had similar situations here (Ohio) and I always advise employees not to compare themselves to others because you never really know what your coworkers situations are.

Without knowing your exact company policy, its likely that they won't approve it... BUT if you took it, you'd either risk discipline or termination. Most of the time, that's what it boils down too... its not as though they can force you to change your wedding, but if you take time without permission, they are within their legal right to fire you.