The advertising industry needs to do more to combat online piracy, at least according to the Congressional International Anti-Piracy Caucus.

In a letter to the Association of National Advertisers, the American Association of Advertising Agencies, and the Interactive Advertising Bureau, four lawmakers urged advertisers to step up their efforts to keep ads from appearing on piracy sites, which generated $227 million in advertising last year.

“Best practices are useful, but greater specificity is needed around preventative measures that participants in the digital advertising ecosystem can, and should, take to avoid the placement of ads on piracy sites, as well as the development of metrics to measure the effectiveness of these steps,” the bipartisan lawmakers wrote.

Reps. Adam Schiff (D-Calif.) and Bob Goodlatte (R-Va.) and Sens. Sheldon Whitehouse (D-R.I.) and Orrin Hatch (R-Utah) expressed appreciation for the efforts made to date, “but note that much remains to be done to operationalize the commitments made and to make them effective in preventing the appearance of legitimate ads on pirate sites, rather than simply responding once they are placed.”

Two years ago, members of the industry pledged to keep their ads off pirate sites. In conjunction with the IAB, the ANA and 4As released a statement of best practices with recommendations for agencies and marketers, such as including specific language in media placement contracts to prevent ads from appearing on illegal sites.

Since then, improved technology allows advertisers to do more, the letter stated. “Marketplace solutions are emerging, and the time is ripe for stakeholders to come together with a renewed focus on developing and implementing a more effective preventive regime,” the legislators wrote.

Advertisers should also remember the mobile ecosystem, the lawmakers noted, “which represents a significant and growing share of online advertising revenues, both for legitimate and pirate sites.”

Why it matters: Response from the industry was positive. “The advertising community is increasingly concerned about how their business practices are being undermined and damaged by piracy and click fraud, which could be as much as a third of what people are spending. The dollars are enormous,” Dan Jaffe, executive vice president of the ANA, told AdWeek. “We have tremendous financial incentives to resolve these issues. As a group, we’ve made this a priority.”