If the spouse did not receive the products or services that the debts are for, then if she can show, with a legal (i.e. court) determination that he was mentally incompetent when he entered into the agreements, she should be able to void the agreements (written or oral) underlying the debts due to lack of mental capacity. This would also apply if she can return any goods or products he received. This is because to void a contract, both parties must be returned to their previous condition or state--you can't keep the other party's stuff and get out of paying them.This means that if the debt is for a service rendered (which cannot be returned, since you can't return the work someone did) or for some good consummed, used up, lost, etc., you can't void the debt, since you can't return what you received.In practice, if you don't currently have a court order or adjudication of incompetence which can be sent to creditors, if they refuse to cancel the debt, this may entail waiting until sued by the creditors, then raising lack of capacity in court, which would have to be proven with medical or psychological evidence.