This means that police officers cannot be more aggressive than is necessary to accomplish a legitimate law enforcement purpose. Contact an excessive force attorney today.We provide the first scholarly analysis of how Fourth Amendment rules concerning use of force apply to medical practitioners who partner with law enforcement. Primarily, the Fourth Amendment's prohibition on excessive force is enforced through a lawsuit filed under Section 1983 of the Civil Rights Act. The Fourth Amendment requires that an officer's use of force be "objectively reasonable. Excessive force is always illegal because it is always unnecessary. Deadly force, on the other hand, while much more serious, is not always against the law. § 1983 based on unreasonable search and seizure under the Fourth Amendment, deprivations of his right to due process, and excessive force. In general, a seizure of a person is unreasonable under the Fourth Amendment if a police officer uses excessive force in making a lawful arrest. Too often, though, police officers use force that is not considered reasonable or necessary.