An insurance policy is stored (101) as a plurality of discrete temporally-sequential policy data revisions. A legally binding revision for a first given date is then determined (102) by identifying all policy data revisions effective on the first given date and choosing a most temporally recent policy data revision temporally prior to a second given date. When a new policy data revision is (103) temporally subsequent as compared to a first policy data revision and also comprises a legally effective date range preceding at least in part an effective date range of the first policy data revision, legally non-overlapping policy data revisions are created (104) for each legally overlapping effective date range as exists between the new policy data revision and all temporally preceding revisions. Each newly-created legally non-overlapping policy data revision comprises changes introduced by the new policy data revision and at least one temporally preceding policy data revision.