The Fourth Amendment of the United States grants people the right to feel secure and protects them from any unlawful searches or seizures. This means that government agents and law enforcing authorities need search warrants to conduct any operation that violates someone's privacy.
There are two major scenarios in which searching someone is allowed. If a judge has issued a warrant, then law enforcing officers have the right to search that person. In some cases, searching without a warrant becomes essential, and the officer has no other choice but to do so. An example of such a scenario would be the search for a weapon after the arrest is made. Even though the officer has no warrant for that search, it is important to make sure the perpetrator is not carrying a weapon.
There are some cases in which the Fourth Amendment does not apply and searching without a warrant is allowed. If the person does not expect to have considerable privacy in the item being searched, the Fourth Amendment does not apply. In all other scenarios, the Fourth Amendment is applicable and used to conduct searches and seizures. However, the Fourth Amendment only applies to government and law enforcing agencies. If a civilian carries out a search and finds something that can be used in court, it will be admissible. On the other hand, any unlawful search lead by a government official will be of no use because whatever is found will be inadmissible in court.
If you have been unlawfully searched by a government official, it is advisable to contact a defense attorney as soon as possible. The attorney will elaborate on your rights according to the Fourth Amendment, and help you get justice for the illegal search conducted on you.