A business that leases real estate and improvements (buildings, etc.) in the form of space for offices, a warehouse, a restaurant, a nail or hair salon, a clothing store, a coffee shop, or other commercial (nonresidential) space will usually be required to sign a written contract known as a commercial lease agreement.

If the tenant (the business occupying the space) who signs a commercial lease agreement fails to pay the rent or continues to use the leased premises for a purpose other than as permitted by the lease agreement (after receiving notice of the improper use), the landlord may have the right to terminate the lease and lock the commercial tenant out of the space by changing the locks.

A commercial landlord’s ability to lock a commercial tenant out of the leased premises—sometimes referred to as one of the landlord’s self-help options or remedies because the landlord may be able to exercise these rights without going to court—depends on the specific language in the written lease agreement and the state's contract law.

For example, a state's contract law may determine if any breach of the lease agreement by the tenant was a material breach that might justify an extreme measure such as changing the locks.

Contract law in most states recognizes an implied duty of good faith and fair dealing between parties to a contract, and a commercial landlord who changes the locks on the leased premises because the tenant is a few days late paying the rent may be in breach of the landlord’s implied duty of good faith and fair dealing.

In Washington State, a business that leases commercial space is typically required to enter into a written commercial lease agreement. This agreement outlines the terms and conditions under which the business may occupy and use the premises. If a tenant fails to pay rent or uses the space in a manner not permitted by the lease, the landlord may have the right to terminate the lease. However, the landlord's ability to lock out the tenant by changing the locks, a form of self-help remedy, is contingent upon the specific provisions of the lease agreement and Washington's contract law. Washington recognizes an implied duty of good faith and fair dealing in contractual relationships, which means that a landlord's actions, such as changing the locks for a minor or brief breach of the lease, could potentially violate this duty. Landlords must exercise caution and typically follow legal eviction procedures to avoid breaching their obligations under the law.