In order to be valid, the pre-nuptial or post-nuptial agreement must be fair and entered into after full disclosure of assets by both parties. Each party should have his or her own independent attorney represent him or her in the preparation of the agreement.  If an attorney does not represent a party, he or she may later be able to void the agreement by taking the position that he or she did not understand what he or she signed.  The agreement must have certain language, and the signatures must be notarized.  Pre-nuptial and post-nuptial agreements are usually found by courts to be enforceable, if they were prepared properly, were entered into by both sides of their own free will with the advice of their own independent attorneys, and are found to be fair.