The search and seizure amendment is basically being read out of the Constitution. From Chris Calton at mises.org:
In 1984, as part of Ronald Reagan’s renewed war on drugs, the Drug Enforcement Administration launched Operation Pipeline. This program was inspired by the strategies employed by state troopers in New Mexico who, after pulling somebody over, asked specific questions designed to determine whether the driver might be a drug trafficker. Combined with the financial incentives of federal grants for drug enforcement and civil asset forfeiture laws, state and local police had strong new incentives to find reasons to stop vehicles and search for drugs. Operation Pipeline was meant, in part, to train officers how to legally harass drivers.
The problem, of course, was the pesky Fourth Amendment, which prohibited warrantless searches without probable cause. The “probable cause” requirement for warrantless searches is conspicuously open to interpretation, but it imposed important constraints on police harassment by placing the burden of proof on the officer to produce specific facts to justify his suspicion. In 1968, however, the Supreme Court granted the first exemption to this constraint by establishing the “stop-and-frisk” rule. In Terry v. Ohio, the Court ruled that as long as a “reasonably prudent man” would believe that a suspect might be armed, the burden of proof to show probable cause is unnecessary.
