This kind of policy provides coverage for claims that may arise from incidents which occurred while you had a policy in force, regardless of when a claim is reported, even if the policy is no longer in force. Thus, occurrence coverage provides long-term continuing protection for the physician.
For example: A physician had an Occurrence policy in effect from January 2000 to January 2008, at which time the existing policy was not renewed. In February of 2009, a patient treated in 2007 filed a claim against the physician. Since the physician had an Occurrence policy in effect in 2007, the company that insured him in 2007 would defend him, based on the 2007 coverage.