What is the main idea of Carroll v. United States? Why is the the idea important to the DLK case?

The main idea of Carrol v. United States is that automobiles can be subject to warrantless searches because they constitute an exception to the principles of a search with a warrant since they are mobile and by the time a search warrant can be obtained from a judge they will easily be removed from the territorial jurisdiction of the locality where the warrant was issued, actively rendering it meaningless. This is known as the automobile exception.

In the Kyllo v. United States case, the suspect was thought by the police to be growing marijuana in his home. Therefore, the police decided to use thermal imaging to scan it (since marijuana plants require very hot ultraviolet lights to grow). Their findings gave them probable cause (a reason to believe that a crime is being committed). However, after this case was brought to the Supreme Court of the US, they considered that using such modern technology infringed the right of privacy of the defendant, as such imaging allows for a view of what is happening inside the home. Since a home is not mobile it was perfectly possible for the police officers to get a warrant to perform such thermal search and thus the warrantless search was unlawful.

Carroll v. US main idea is to permit a warrantless search of a car in the presence of a probable cause, attending to the fact that the vehicle can be removed from the area before a search warrant is obtained.

At DLK case the big discussion is if the Fourth Amendment has any exceptions in the case of search warrants, because we are talking again about a case that evolves the concept of "searching" itself in light of new technologic developments.

At DLK case the decission that thermal imaging of a home doesn't constitute a search is a strong legal precedent to argument that if in the future thecnology can create sophisticated equipements to invade one's right to privacy, the fourth amendment can still protect citizens against them.