Last week, at the Port of Miami, federal agents rousted sleeping vacationer Hope Clarke from her cruise ship cabin, handcuffed her, and hauled her off to jail. Her crime? A year ago, while visiting Yellowstone National Park, Clarke had forgotten to put away her marshmallows and hot chocolate, and authorities cited her for “improper food storage.” A Wyoming federal court issued a bench warrant for failure to pay the $50 fine, and Immigration and Customs agents enforced it last Friday during a security check when Ms. Clarke’s cruise ship docked.

After seven hours in jail, enduring catcalls and vulgar propositions from male inmates, a weeping Clarke appeared before magistrate judge John O’Sullivan in leg shackles. It turned out that she had already paid the fine. She’d been required to before she left Yellowstone that day. When the assistant U.S. attorney protested that there might be some “discrepancy” between Clarke’s story and the paperwork, Judge O’Sullivan responded tartly, “Seven hours in jail, I think, is a suitable punishment for leaving marshmallows out at a camp site.”

Of course, Ms. Clarke isn’t the only peaceable citizen to get the Hannibal Lecter treatment from law enforcement. Examples are legion. Last November, police in Goose Creek, South Carolina raided Stratford High School, looking for drugs. Guns drawn, they threw some kids to the ground and restrained others in plastic handcuffs when they didn’t get down quickly enough. They didn’t find any drugs. In April 2002, the Palo Alto, California police department booked (complete with fingerprints and mug shots) a 61-year-old grandmother for the crime of letting her hedges grow over two feet high. And in 2001, the Supreme Court heard the Atwater case, in which a Texas police officer pulled Gail Atwater over for driving without a seatbelt, handcuffed her in front of her crying children, and drove her to jail (without buckling her seatbelt for her, oddly enough). Ms. Atwater argued that this outrageous treatment violated the Fourth Amendment’s bar on “unreasonable searches and seizures.” She lost.

However abominably the police behaved in these cases, we can’t blame them alone. These cases are part of an ongoing and dangerous trend that analyst James DeLong has called “the criminalization of almost everything.” Where once the criminal sanction was reserved mainly for serious, morally culpable offenses, today ambitious legislators and prosecutors invoke it for trivialities. And for the most part, judges have been too timid to restrain them.

In some cases, lawmakers criminalize matters more properly handled through civil lawsuits. In others, they criminalize behavior that shouldn’t be the subject of any legal sanction at all. That weakens the moral force of the criminal sanction and breeds contempt for the law.

At the state level, everything from peddling “untested sparklers” (Florida) to wearing low-rise jeans (which can get you up to six months in prison in Opelousas, Louisiana) is a criminal offense. At the federal level, the problem is, if anything, worse. There are now over 4,000 federal crimes, an increase of one-third since 1980. Those crimes are spread throughout tens of thousands of pages of the U.S. Code, with the result that even teams of legal researchers — let along ordinary citizens — cannot be sure what, exactly, the law forbids.

Innocent citizens minding their own business ought to be able to rest assured that they won’t be handcuffed and humiliated by agents of the state. Instead, as Harvard Law professor William J. Stuntz warns, we’re coming “ever closer to a world in which the law on the books makes everyone a felon, and in which prosecutors and police both define the law on the street and decide who has violated it.” Reversing that trend is an enormous task, but an absolutely vital one.