Do receipt checks violate your rights?

This post comes from MSN Money's Liz Pulliam Weston.

Receipt checks -- where store employees review your receipt at the exit to make sure you've paid for everything in your cart or bags -- are typically voluntary.

Somebody needs to let the store employees know that.

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For a few years now, The Consumerist has been documenting skirmishes between customers and employees who refuse to take "no thank you" for an answer. Shoppers reported being physically detained, having their paid-for items taken away, and being threatened with arrest (although sometimes it was the shopper who called the cops, as one guy did after a manager took his merchandise).

The Consumerist makes the argument that this is a civil liberties issue. Indeed, while the law varies from place to place, U.S. retailers generally aren't allowed to detain you unless they have good reason to believe you've stolen something -- and refusing to present your receipt doesn’t constitute probable cause.

"In general, the store can't force someone to show their receipt," says Joseph LaRocca, senior asset protection advisor for the National Retail Foundation, which calls itself the world's largest retail trade association. "The checks at the door are really designed to be a preventative measure and a customer service measure."

Say what? La Rocca says receipt checkers may spot overcharges and help customers save money that way. But stores mainly use the checks to combat the $12.5 billion they lose to shoplifting annually, as well as miscellaneous losses from clueless customers who wander out without paying for, say, that case of beer in the bottom of their cart.

Less theft and loss can translate into lower prices for consumers, LaRocca says. There's also the matter of sales taxes. Thieves, you see, are taking merchandise that could otherwise generate revenues for state and local governments.

Which is all well and good, but if you want to say no to a receipt check, you're not supposed to be accosted, detained, harassed or -- in one extreme case in China -- beaten to death.

The exception -- to being detained, not killed -- is if you've signed an agreement that makes receipt checks part of the package, as is the case at membership warehouses like Costco. (Costco's policy on receipt checks and other searches is outlined here, on page 29. Oh, and you're also supposed to mind your kids and not leave them unattended. I’m talking to you, clueless mom on the cell phone.)

Costco Chief Financial Officer Richard Galanti says he gets only one or two complaints a year about receipt checks. Members understand that the reviews help prevent shoplifting, which in turn helps Costco keep prices down, he says. For its part, Costco tries to make the process fast, adding a second receipt-checker at peak times to reduce the wait.

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"It's our job to make sure it's expeditious," Galanti said. "Nobody wants to be kept waiting."

True enough. And some people have no problem waiving their rights for a big corporation's benefit. The receipt-checking horror stories on Consumerist usually feature comments from readers annoyed that a shopper might slow down the line by asserting his or her right to say no.

But personally, I don't like being treated like a criminal. So I generally shop at places that don't treat me that way.

And I think the stores that keep showing up in the Consumerist -- especially Wal-Mart -- need to do a better job of familiarizing their receipt-checking employees with the reality that receipt checks are voluntary. The chain should probably work on its media relations, as well -- Wal-Mart didn't return a call or e-mail requesting comment for this column.

Liz Pulliam Weston is the Web's most-read personal-finance writer. She is the author of several books, most recently "Your Credit Score: Your Money & What's at Stake." Weston's award-winning columns appear twice weekly, exclusively on MSN Money. She also helps middle-class families cope at Building a Brighter Future.

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