“Excuse me, ma’am. Can you prove that the money on your Starbucks gift card wasn’t procured through a marijuana sale?”

An odd, unanswerable question. And yet this is exactly the kind of question that Oklahoma police, armed with a new device, will soon be asking, with an eye toward seizing the cash on the cards.

The device is known as an ERAD (Electronic Recovery and Access to Data) machine, and it can access the money on prepaid debit and gift cards that are swiped through it. The police insist the devices will only be used against drug traffickers and identity thieves, but the history of due-process-free civil seizures suggests otherwise.

During the past year, Oklahoma has become a flashpoint in the nationwide debate about a law enforcement procedure known as civil asset forfeiture. Civil forfeiture allows the police to seize property or cash on mere suspicion that it’s connected to criminal activity, even when they lack sufficient evidence to actually charge the suspect with a crime. And in most jurisdictions, the seizing agency even gets to keep the proceeds of their seizures rather than depositing the money in some general fund.

Such perverse incentives have predictably led to a string of abuses around the country, leading to efforts at reform or outright abolition. In Oklahoma, a reform effort led by State Sen. Kyle Loveless stalled out after an organized campaign by law enforcement suggested that forfeiture reform would strengthen the Islamic State in Iraq and Syria and lead to Mexican drug cartels hanging decapitated corpses from Oklahoma bridges.

The experience in neighboring New Mexico, which abolished civil forfeiture last year, suggests those claims may be exaggerated. No terrorists; no decapitated bodies littering the streets. Just fewer instances of forfeiture abuse.

In the absence of substantive reform, civil forfeiture abuses in Oklahoma continue to pile up. A county sheriff threw a man in jail and wouldn’t release him until he signed over the $10,000 in cash he’d been carrying as drug proceeds.

A Christian band from Burma had tens of thousands of dollars, earmarked for refugee orphanages and schools, taken by police because the band manager was carrying the money in separate envelopes. And now Oklahomans who carry cash on gift cards or prepaid debit cards will be at risk as well.

Police officers don’t deny that they’ve replaced a presumption of innocence with the burden of disproving guilt. “If the person has proof that it belongs to him for legitimate reasons, there’s nothing going to happen. We won’t seize it,” says Lt. John Vincent of the Oklahoma Highway Patrol.

But it can be difficult or impossible to prove your money isn’t tied to some criminal enterprise, especially when standing on the side of the road. And this logical conundrum is precisely what our legal system seeks to avoid by placing the burden of proof on the government in the first place.

The situation has gotten so bad that some companies have begun boycotting Oklahoma for fear that their drivers will be targeted.

In the Wagoner County bribery case, the sheriff’s attorney implied that the “sign over your money or stay in jail” tactic was a routine law enforcement behavior in civil forfeiture terms. Many reform advocates would agree. The line between legal civil asset forfeiture and illegal extortion is often hopelessly blurred.

Our Founding Fathers recognized this danger explicitly, and so they separated the power of the purse from the sword of enforcement. They also codified a presumption of innocence and the right to due process into our legal framework, so that no person would be punished for the inability to prove what he or she didn’t do.

Ultimately, it’s not law enforcement’s job to handcuff itself, and it’s naive to expect police departments to limit their own use of available technology. Police are not uniquely corrupt, but they are human, and humans respond to incentives.

Legislatures and courts have an obligation to check the excesses of law enforcement, and civil asset forfeiture has escaped their attention for too long. Several states have reformed their civil forfeiture laws. Some, like New Mexico, have abolished the practice entirely. Others have neutralized the perverse profit motive by directing all forfeiture proceeds into the state general fund.

Still other states, like Oklahoma, have decided to allow these abuses to continue. And so they have. And so they will.

Adam Bates is a policy analyst with the Cato Institute’s Project on Criminal Justice.