Abstract: A method for mitigating false positive type errors while applying an information leak prevention policy to identify important information and to prevent outward leakage. A positive criterion is defined for a positive set, and a negative criterion for a negative set of benign traffic. An ambiguity set contains items showing indications for both positive and negative sets. An ambiguity resolution criterion allows ambiguous items to be placed in/removed from the positive set or negative set. Each information item is searched for matches with the positive set. Each item in the positive set is checked for membership in the ambiguity set. The ambiguity resolution criteria are used for each member of the ambiguity set and to remove items from the positive set accordingly. The leak prevention policy is applied for all items remaining in the positive set thus protecting the important information.