If a creditor puts a lien on your house, you'll have a hard time selling or refinancing it unless you pay off the lien. That may seem unfair, especially if it's your spouse's creditor applying the lien, but it can happen. It may depend on which state you live in, as laws on spousal debt vary around the country.
You'll need to look at the spousal laws in your state to determine whether a lien can be placed on your home as a result of your spouse's debt.
In community property states, you and your spouse are considered to own all marital assets and debts in equal shares. If you bought a house after you married, the home is considered community property, even if your name is on the title and your money built up the equity. Because it's a joint asset, your spouse's creditors can put a lien on the house for his or her debt.
Also keep in mind that since you own half your spouse's debt, it's typically "your" debt. If, however, you bought the house before the marriage, and if your spouse incurred the debts before your marriage, the house is generally safe from your spouse's creditors, unless you retitled it to give him or her co-ownership.
Most states apply common law rather than community-property rules to marital debts. Common law says that your spouse's debts and income are his or hers alone, with the exception of "family expenses" that benefit both spouses. There's no exact definition of "family expenses," but Illinois, for example, has held that the term covers spousal spending on medical bills, clothing and the family home. So, for example, if your spouse has unpaid medical bills, the creditors could come after your house.
Generally you're not responsible for any debts your spouse ran up before you got married. In a community property state, your spouse's creditors can go after his share of any jointly titled assets to collect, but not your separate property. Another special case is if you make your spouse an authorized user on a credit card. If he or she then runs up a few thousand dollars and defaults, legally you're the account owner, which means the credit card company will try to collect from you.
If you're seriously worried about your spouse's spending, a written agreement that you don't assume responsibility for each other's debts can protect you. Either a pre- or post-nuptial agreement will work, as long as you both sign. If you don't have an agreement, your spouse's creditor still has to go to court to win a judgment authorizing the lien. You can try convincing the judge that a lien on your property isn't appropriate, for example, stating that the debt isn't really a family expense.