It happened in the US of A. Twice that I know of…Im sure many more cases exist. As long as the good or service provided is legal, any oral or written agreement between two parties can constitute a binding legal contract. In both cases, the nikah namah was read by family, mehr was agreed upon from before and made part of the contract. During the divorce, the guys tried to get out of it by refusing to pay and she hired a lawyer.
Your nikah namah is signed by both you and your husband, in the presence of witnesses. It is a contract. Of course, both marriages were registered in the US also.