Even though nearly four times as many arrests were made in 2007 than in previous years, fewer than 100 supervisors or hiring officials were charged in criminal cases out of about 4,900 arrests involving illegal workers, providers of fake documents and others in the past year, The Washington Post reported Tuesday.

Immigration experts call the data a testament to the Bush administration's limited success in stopping illegal hiring by corporate employers.

"I know what it takes to get a criminal case," said Sen. Claire McCaskill, D-Mo., a former state prosecutor and member of the Senate Homeland Security Committee. "Why is it that hundreds of bar owners can be sanctioned in Missouri every year for letting somebody with a fake ID have a beer, but we can't manage to sanction hundreds of employers for letting people use fake identities to obtain a job?"