A system and method for filtering unwanted Internet Protocol traffic based on blacklists receives a first blacklist containing a first plurality of Internet protocol addresses associated with unwanted Internet traffic. The system also operates a first plurality of access control lists adapted to block the unwanted Internet traffic from one of the first Internet protocol addresses listed in the first blacklist. The system also assigns a first weight to each of the first Internet protocol addresses based on a reliability of Internet traffic from each of the first Internet protocol addresses. Additionally, the system reduces a first number of the first access control lists to optimally trade off a number of desirable Internet protocol addresses blocked with a number of bad Internet protocol addresses blocked based on the first weight of each of the first Internet protocol addresses.