This law varies by state but is generally a limitation of a lender's rights to enforce and collect debt that is secured by real property. A one-action rule typically requires a lender to complete a judicial or non-judicial foreclosure on the real property collateral before it can obtain a deficiency judgment against the borrower or take other action to collect against a borrower's assets. A one-action rule may prevent a lender from suing a guarantor under a guaranty if it is secured by the real property collateral.

There are advantages and disadvantages in pursuing a judicial or non-judicial foreclosure. For example, in some states, such as California:

The rule is meant to prevent multiple enforcement actions that may harass a borrower. If a lender violates the one-action rule, it typically loses its secured position in the real property collateral.

For more information on the one-action rule and lender remedies, see Practice Note, Borrower Defaults and Lender Remedies in Commercial Real Estate Loans.