Policy checks are the rules an access system uses to decide whether a request should be allowed. They can evaluate user identity, device health, location, time, network, or application risk before granting access. In zero trust designs, policy checks are the gate between authentication and actual access, so a valid login alone is not enough.
They matter because they reduce unnecessary trust and help limit blast radius if credentials are stolen. In defense, policy checks can block outdated devices, suspicious geographies, or unmanaged endpoints, and they can force step-up authentication or deny access entirely. In attacks, criminals often try to bypass or weaken these checks by stealing tokens, abusing misconfigured rules, or targeting legacy VPN paths that grant broad access after login. Strong policy checks make access more conditional and easier to revoke when conditions change.