What must a service level agreement (SLA) define?

SLAs are not legally binding documents; legally enforceable obligations between organizations are established through formal contracts or underpinning contracts, not SLAs.

Describing an SLA as imposing legally binding contractual responsibilities on the service provider alone is incorrect - an SLA is an agreement, not a legal instrument, regardless of which party's obligations are referenced.

While SLAs reference the customer relationship, defining mutually binding contractual responsibilities for both parties describes a formal contract, not an SLA as defined in ITIL.

Under ITIL, an SLA is defined as an agreement - not a contract - between an IT service provider and a customer. It sets out the key service-level targets (such as availability and response times) and the responsibilities the provider commits to meet, without creating mutual legal obligations enforceable in a court of law.