While Justice Scalia was known as an arch-conservative, a believer in the "original intent" of the Constitution, that view of originalism worked to the benefit of defenders of the Fourth Amendment, and as a result, many criminal defendants.
This is because of the explicit nature of the protection of the Fourth Amendment in the Constitution. Prosecutors are sometimes prone to play fast and loose with the mandates of the Constitution in an effort to win a conviction. Justice Scalia was willing to point out situations where they crossed the line from prosecuting a crime to attempting to manipulate the Constitution for their benefit.
He ruled against the police when they attempted to use technology in an effort to sidestep the Fourth Amendment's protection from warrantless searches of homes. In a case where police used thermal imaging sensors to detect heat emitted from a home where marijuana was being grown, he noted that substituting technology for the capacity of humans turned observation into a warrantless, and, therefore, illegal, search.
He sometimes dissented in these cases, as in a recent case that allowed a DNA sample to be taken during booking of a criminal suspect. He noted such a policy would lead to more crimes being solved, but as he often did, he would follow such logic to its conclusion to highlight its invalidity, here asking why not swab all those who fly or apply for a drivers' license?
He reminded the Court "suspicionless searches are never allowed if their principal end is ordinary crime-solving" and that is the "heart of the Fourth Amendment."
This last part is too often forgotten. The Constitution does not exist to further crime control or make the job of the police easier. It is to protect fundamental rights of all Americans.
In that regard, Justice Scalia will be missed.
Source: slate.com, "Antonin Scalia’s Other Legacy," Robert Smith, February 15, 2016