They chose not to do so. And the courts are no help, because generally speaking, you can't sue the government unless there's a specific law allowing you to do so (sovereign immunity). The police as individuals are generally immune from civil suits unless they violated some clearly established right (qualified immunity).
Perhaps it should be, but the courts have not agreed. See Pena v. Los Angeles for an example of an appellate case that rejected this argument. It found that a "police power" exception to the takings clause applies in such cases.
