NO it is not illegal to get married while in the US on a tourist visa. If she is not planning on remaining in the US after the wedding, there is no harm at all. However, it does not really make sense to me why you would get married and then have her go back home, since you will then need to petition for her anyway in order for her to be able to immigrate to the US and be with you. That process will also take about 9-12 months and during that time, she may not be permitted to enter the US as a visitor since she will be seen as having immigrant intent.
Answered on Mar 14th, 2013 at 2:42 PM