Under President Barack Obama, the Federal Bureau of Investigation (FBI) has dramatically increased its use of a controversial provision of the Patriot Act (pdf) to pry into the business records of U.S. citizens.

The probing involves Section 215 of the Patriot Act, which permits the FBI to obtain business records and other “tangible things”—including “books, records, papers, documents and other items,” as part of a terrorism or foreign intelligence investigation.

In 2009, the FBI reported to Congress that it had used Section 215 only 21 times to access business records.

That total had soared by last year to 212 requests—a 1,000% increase.

Experts say this indicates a broadening interpretation of the provision on the part of government, so that it is being applied not only to targeted individuals but to Americans who have no apparent ties to terrorist activity.

Robert Chesney, a top national security lawyer at the University of Texas Law School, said he was surprised to learn how much the use of Section 215 had gone up over the last four years.

“Most people who followed this closely were not aware they were doing this,” Chesney told NBC News. “We’ve gone from producing records for a particular investigation to the production of all records for a massive pre-collection database. It’s incredibly sweeping.”

Section 215 is getting renewed attention since it was discovered to have been used in the recently disclosed government order to force Verizon to turn over millions of its telephone records.

This week the ACLU participated in a court filing that requested the surveillance court to release its classified legal opinions that form the basis for the expanded use of the Patriot Act’s Section 215.

The request references a 2011 quote from Senator Ron Wyden (D-Oregon): “When the American people find out how their government has secretly interpreted the Patriot Act, they will be stunned and they will be angry.”

-Noel Brinkerhoff, Danny Biederman

To Learn More:

FBI Sharply Increases Use of Patriot Act Provision to Collect US Citizens' Records (by Michael Isikoff, NBC News)

Reform the Patriot Act | Section 215 (American Civil Liberties Union)

Obama Administration Orders Verizon to Turn over all Call Records (by Noel Brinkerhoff, AllGov)

11 Secret Documents Americans Deserve to See (by David Wallechinsky, AllGov) 

Opposition Grows to Obama’s Refusal to Reveal Secret Patriot Act Powers (by Noel Brinkerhoff, AllGov)

Civil Liberties Groups Add to Lawsuits against Justice Dept. over Secret FBI Patriot Act Power (by Noel Brinkerhoff and David Wallechinsky, AllGov)