TWO DECADES AGO, if Americans thought about human trafficking at all, it was usually in the context of Russian or Ukrainian girls and young women enslaved and transported for forced prostitution. Thanks to a dedicated band of human rights advocates who have spread the gut-wrenching stories of victims, trafficking is understood today as a global phenomenon exceeding 20 million cases each year and including forced and bonded labor among women, men and children.

The modern-day abolition movement has made gradual progress, and not just in raising awareness. In 2000 Congress passed the Trafficking Victims Protection Act, offering protection in the United States to victims of all forms of trafficking. The Palermo Protocol, an anti-trafficking treaty, has been ratified by 142 countries, and 128 have enacted laws criminalizing the practice.

On Monday, the State Department released its annual Trafficking in Persons (TIP) report, assessing the efforts of governments — including, thanks to Secretary of State Hillary Rodham Clinton, the U.S. government — in combating trafficking at its sources, on its routes and destinations. The report’s tracking system is useful, if imperfect, and the combination of public shaming and threatened sanctions has had an impact, even if diplomatic imperatives at times unduly influence the rankings.

The State Department’s mantra of “prevention, prosecution and protection” is an intelligent, interconnected prescription to stem trafficking and recognize its root causes, which include economic marginalization, public corruption and consumption by law-abiding citizens of goods produced by forced labor.

However, prosecution warrants higher priority. Last year, according to the report, only 6,017 cases of trafficking were prosecuted. That was fewer than in 2005 and 2004 (6,178 and 6,885, respectively) — and a shamefully meager tally, given the millions of victims not being helped and the thousands of pimps and slave traders not being brought to justice.

The transnational nature of these crimes often makes them hard to try in court. Investigations and trials move at an intolerably sluggish pace. More use must be made of new forms of evidence, such as wiretapping of SMS text messages for drop-offs of slaves. Government officials who accept bribes in return for not pursuing traffickers or who themselves participate in forced sex or labor rings must be pursued.

We are a long way from the last hurrah of the global abolitionist movement. But this year’s report includes the goal of “moving toward a decade of delivery.” That’s an essential objective for dealing with these most horrific of crimes against the most vulnerable of human beings.