Increased cooperation among investigators in different nations is believed to be a primary reason for the escalation, say lawyers who handle these cases. German prosecutor Anton Winkler says international legal assistance has greatly improved in the last 15 years, particularly in corruption and bribery cases.

"A decade ago, requests for international legal assistance meant months of waiting or no answer at all. That has changed," Winkler said in a telephone interview. He says the quality of assistance varies from country to country, depending on a variety of factors, including bilateral treaties and agreements.

Another factor: More companies are voluntarily turning over evidence of wrongdoing in the hope of getting leniency from prosecutors. The 2002 Sarbanes-Oxley law in the U.S., which requires executives to certify that their company's financial disclosures are accurate, has also led to more disclosures. A bribe that is mischaracterized as a legitimate payment to a consultant, for instance, can be considered a misleading entry on the corporate books.

Companies are getting the message. Having a written antibribery policy that isn't enforced in a muscular manner won't be enough to protect a company, says Shearman & Sterling's Newcomb. "Real investigations are happening, and real fines are being paid," he said.