The chilling loophole that lets police stop, question and search you for no good reason

This article originally appeared on AlterNet.

Checkpoints occupy a unique position in the American justice system. Atthese roadside stations, where police question drivers in search of the inebriated or illegal, anyone can be stopped and questioned, regardless of probable cause, violating theFourth Amendments protection against general warrants that do not specify the who/what/where/why of a search or seizure. Though the Supreme Court agrees that checkpoints skirt the FourthAmendment, the Court has been clear that the special needs checkpoints serve, like traffic safety andimmigration enforcement, trump the slight intrusions on motorists rights.

We have checkpoints for bicycle safety, gathering witnesses, drug trafficking, illegal immigration and traffic safety.Many states,like California, require cops to abide by neutral mathematical formulas when choosing which drivers to pull over (like 1 in every 10 cars). In reality, these decisions are left to the discretion of individual police officers, which results in a type of vehicular stop and frisk.

Thats why people in Arizona havesuedthe Department of Homeland Security for its wantondeployment of immigration checkpoints in their state.Among their complaints are racial profiling, harassment, assault and unwarranted interrogation,and detention not related to the express special need of determining peoples immigration status.

A key legal detail about checkpoints is that they cannot be used for crime control, as that would require individualized probable cause. But legal scholarsarguethat non-criminally-minded checkpoints are also illegal. They point out that the FourthAmendment protected the colonists from being searched for non-criminal wrongdoing. Doing nothing wrong at all, they argue,is not grounds to be searched or haveyour property seized.

Regardless, unlike DUI checkpoints, these immigration checkpoints, expanded by the 2006Secure Fence Act, are only allowed within 100 miles of the continental United States border. But thats abig perimeter. Nine of the countrys 10 largest cities, entire states and some two thirds of the US population reside within this constitutionallyexempt zone.

At these checkpointssome of which have becomepermanentfixtures on the highwaypeople are forced to stop when flagged down, againregardless of probable cause. But the extent to which people are legally obliged to answer officers questions isunclearand seemingly arbitrary. Not surprisingly, the militarysimmigration checkpoints havegarneredoutspoken criticism from across the political spectrum.Legalized by the Supreme Court in1976, these checkpointsseem to have taken on a newmomentum in the post-9/11era. (Private militias have eventaken tosetting uptheir own versions.)

DUI checkpoints, on the other hand,deemedconstitutional in 1990, monitor roadwaysin38 states. But they have been outlawed by12 othersthat have invoked states rights to increase federal civil liberty protections.In the Courts 1990opinion, Chief JusticeWilliam Rehnquist wrote that states interest in eradicating drunk driving is indisputable and that this interest outweighed the measure of the intrusion on motorists stopped briefly at sobriety checkpoints, which he described as slight.

In the dissent, William Brennan reminded the Court that, some level of individualized suspicion is a core component of the protection the Fourth Amendment provides against arbitrary government action. In pulling people over at random, checkpoints remove this individualized component.

Today, the practice seems to be experiencing a renaissance of sorts. With the help of local police, private government contractors have used the tactic to collect anonymous breath, saliva and blood (DNA) samples of American motorists for the federally fundedNational Roadside Survey of Alcohol and Drugged Driving. Participation in the survey is voluntary, despite the confusion that may come with uniformed police asking for bodily fluids. Motorists are offered $10 for cheek swabs and $50 for blood samples. These practices have sparked considerable publicoutrage; law enforcement officials inSt. Louis, Missouriand Fort Worth, Texashavestatedtheir intent to limit their future participationin the study.