they can declare them to be invalid or void based on some legal stipulation. even the smallest problem with a contract can be grounds for having it invalidated by a judge. this is one reason it is a good idea to keep prenups very simple and very specific. if your prenup is vaguely worded so you could apply it to whatever you wanted, a judge will say it wasn't made in good faith and throw it out. if your wife can present evidence that you coerced her into signing it, he will throw it out. if the document makes claim to assets you don't have, the judge will say it is erroneous and ignore the entire document.  keep it simple, keep it specific.
United States