Here's an arresting allegation: More slaves are now imported (though the current word for this is trafficked) into the United States annually than were imported in an average year during the American colonial era.

That is one of the talking points used lately by the author of an arresting new book on global slavery, "A Crime So Monstrous: Face-to-Face with Modern-Day Slavery," by E. Benjamin Skinner.

In fact, of course, at the height of the legal slave trade in the 19th century, many more African slaves were "trafficked" to the United States than are arriving now, but globally there may be more people in slavery than ever. Still, it comes as a shock to read Skinner's accounts of the people - the U.S. State Department estimates 600,000 to 800,000 brought across international borders each year - forced to work around the world under threat of violence for no pay.

In the United States, the best estimates indicate that 40,000 to 50,000 people are held in slavery at any given time, with about 17,000 people brought into the country and forced to work for nothing every year. The largest single category of them are forced to work as prostitutes, but a majority are domestic servants or some other form of forced labor.

What is remarkable about Skinner's account is its geographical depth and immediacy. He negotiates with one Benavil, a slave trader in Haiti, and arranges to buy a 9-year-old girl, who will do unpaid housework for him and also serve as what Benavil delicately calls a "partner." Skinner does not proceed with the transaction.

In Bucharest, a pimp offers to sell him a young girl in exchange for a used car. He meets a 46-year-old man in India, and sees the gravel pit where his master has forced him to work 14-plus hours a day virtually all his life.

And in Florida, he meets Williathe Narcisse, trafficked into the country from Haiti at the age of 9 and held in domestic bondage until she was freed three years later. She was regularly beaten and repeatedly raped by a member of the family that "owned" her.

Reasonable people believe that slavery is an atrocity, and in 2000, Congress passed a piece of landmark legislation, the Trafficking Victims Protection Act, that vastly increased the U.S. government's power to pressure countries where slavery is common and to fight the slave traffickers at home.

But now a well-intentioned but arguably wrongheaded step is being taken in the struggle. It comes in the form of a new law passed by the House of Representatives in December - known as the William Wilberforce Reauthorization Act, after the British member of Parliament who led the fight to abolish the slave trade in England in 1807 - that has also been hailed as a landmark by its supporters.

The new law focuses attention on sex slavery in particular, giving new powers to the Justice Department to prosecute pimps at the federal level who, before, would have escaped attention.

The bill, said Representative Chris Smith, a New Jersey Republican who was among its co-sponsors, "will help the U.S. expand our leadership role in the global effort to free the victims and punish the pimps and thugs who put them into bondage."

A noble effort. And yet, the Justice Department, the National Association for the Advancement of Colored People, the American Civil Liberties Union, the National District Attorneys' Association and numerous experts on slavery, including Skinner, feel that the new law is a bad idea. Why?

Basically, because it overreaches. The bill implicitly accepts the notion, advanced by a strange-bedfellows coalition of evangelical Christians and feminist activists, that all prostitution is slavery. The point is certainly debatable, but in the present instance the vastly broader definition is likely to have the effect of weakening the struggle against the worst abuses.

The bill so emphasizes sex slavery that some people whose antislavery credentials can't be doubted worry that it will dilute the efforts of the Justice Department to prosecute both domestic labor enslavement, like that of Williathe Narcisse, and, worse, to impede prosecution of child abuse.

The new law, for example, renames the "Child Exploitation and Obscenity Section" of the old law the "Sexual Exploitation and Obscenity Section," and according to Justice Department officials, it will force two dozen federal task forces that now concentrate on child prostitution to expand their efforts to adult prostitution.

The Wilberforce Act also makes all organized prostitution a form of slavery - whether of the $1,000-an-hour call girl version or the abused, drug-addicted streetwalker type forced to turn all her earnings over to her pimp. It also removes earlier criteria used in the definition of slavery - namely that force, fraud or coercion had to be involved - so that even a woman who chooses to be a prostitute (and there are such women) would be deemed a slave. The new law could even have the effect of criminalizing prostitution in the one state where it is legal, Nevada, though that would depend on how federal prosecutors decided to interpret it.

"This would equate every instance of adult prostitution with the worst forms of labor and sexual exploitation, the ones often called modern-day slavery," said Laurence Rothenberg, a deputy assistant attorney general.

"It's very hard to be against something called the Wilberforce Act, which purports to give the Justice Department more tools to combat slave trafficking," Skinner said, explaining how the House bill passed by a vote of 405 to 2, with very little debate.

"But by equating ordinary, non-coerced prostitution with slavery in all cases, the Justice Department is going to have to go after the non-violent, mom-and-pop pimps who, until now, were in the province of the states," Skinner said.

"Prostitution is always degrading, often brutal, and I'm all for arresting pimps at all levels. But I'm not for the Justice Department using its limited resources and only going after the low-hanging fruit, when they should be going after the hidden monsters that enslave girls like Williathe."

Fortunately, the Senate seems likely to take into account some of the objections to the new law, so it remains possible that a more moderate piece of legislation will result - one that leaves the main initiative to combat prostitution with the states, and doesn't commit the moral excess of defining every act of organized prostitution as a violation of federal antislavery laws.