Yes, a cohabitation contract signed before marriage is automatically considered a marriage contract if the spouses marry. Most unions also contain a clause stating that the contract remains valid and enforceable if the spouses marry in the future. A national contract is not binding where it can be proven that it was signed under duress or is grossly unfair, or if one of the two persons has not provided the other person with a full financial disclosure. However, courts give competent adults a high degree of autonomy to adopt their own rules, however unfair they may be, so it can be difficult to identify any of these reasons for the cancellation of a domestic contract. That is why legal advice before the agreement is signed is so important. Lord Atkin`s judgment justified the issuing position that, with regard to national agreements, it is considered that they should not be legally binding. "The parties [at Balfour vs. Balfour] lived together in Un DerUt. In such cases, their national rules are generally not intended to establish legal relationships. It is quite different if the parties do not live in Derity, but are separated or about to separate.
They negotiate zealously. They do not rely on honourable agreements. Presumably, they intend to establish legal relationships. The willingness of an innocent party to go to court to enforce a broken agreement should not be considered conclusive as to the intention to establish legal relations. There are many minor trade agreements for which the parties are unlikely to feel that it would be helpful to have the courts fix an offence. However, the parties clearly intend to create binding commitments. Moreover, even in the case of large commercial transactions, the parties often prefer to settle disputes in a manner that does not involve the use of lawyers. This does not mean that they do not intend to make their agreements legally binding. An internal agreement between two people - usually in a family relationship - is an agreement that defines their rights and obligations. However, contrary to normal contractual conditions, it is considered, in domestic contractual cases, that there was no intention to enter into a legally binding agreement and that the courts are often reluctant to enforce it.
While there is no requirement that you and your spouse hire a lawyer, it is in your best interest to obtain independent legal advice before signing a national contract.