Dick Price, in his recent blog, lists ten reasons why a pre-nuptial agreement might not be enforceable. He quotes Stephen Worrall from his blog. An "unenforceable" agreement means it's not worth the paper it's written on! The courts will not enforce the terms of the agreement. You should use the agreement to start a fire because it's otherwise useless.
Here is their list
* No written agreement
* Not properly executed
* You were pressured
* You didn't read it
* No time for consideration
* Invalid provisions
* False information
* Incomplete information
* No independent counsel
Although Dick and Stephen are writing about Texas and Georgia law, the same is true for Ontario.
The most important aspect of a marriage contract or pre-nuptial contract to ensure it is enforceable is that the negotiations are done properly. Courts like to respect contracts but only if both parties knew what they were doing when they signed the contract and did it voluntarily. A marriage contract or pre nuptial agreement or co-habitation agreement is really just a contract between two people so is treated the same way by the judges.
There should be full disclosure of all assets and income for both parties. In fact, I list the major assets and income in the agreement itself so there is no question that it was disclosed. If assets are not fully listed, it is possible that your spouse may say "If I knew my spouse was worth so much money, I would not have signed the agreement".
I also strongly recommend that both parties have independent legal advice. Otherwise, your spouse might try to wiggle out of the agreement on the basis of "I didn't understand all that legal mumbo jumbo."
Ontario courts are certainly willing to respect pre-nuptial agreements regarding property issues. A typical agreement might say "property in my name is mine, property in my spouse's name is my spouse's property". These types of agreements are usually respected if the agreement has been entered into voluntarily and there has been full disclosure.
The courts are less willing to respect an agreement that results in the waiver of spousal support. Judges have a difficult time seeing one spouse impoverished when the other is wealthy. If they can find a way to set aside an agreement that waived spousal support, they often will do it.
The best advice about pre-nuptial agreements is talk to a lawyer and do it properly.