The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
The 4th Amendment is important to the criminal justice system because it sets out many of the most important rules that law enforcement must observe as it tries to maintain order in our society.
The 4th Amendment protects the rights of the people against the police and other government entities. It prevents them from searching our homes or our persons without warrants. It specifies that the police will need probable cause to get a warrant and that they can only look for the things specified in the warrants.
This affects the criminal justice system because it forces the police to work harder to get the proof they need to convict criminals. They are not simply free to stop and search anyone whom they suspect of crimes. They are not free to search our homes just because they think they might possibly find something incriminating. This makes the job of the police harder, but it also protects us and our rights. This is why it is important and relevant.