This Wired article details how the FBI used a grand jury to subpoena some medical records legally – then returned the records and inappropriately used a national security letter (NSL) in an attempt to get the very same records.
Once the university rejected the NSL, as it should have, the FBI went to Congress citing the incident as evidence of their need for greater power.
Counterterrorism officials in FBI headquarters slowed an investigation into a possible conspirator in the 2005 London bombings by forcing a field agent to return documents acquired from a U.S. university. Why? Because the agent received the documents through a lawful subpoena, while headquarters wanted him to demand the records under the USA Patriot Act, using a power the FBI did not have, but desperately wanted.
Under the USA Patriot Act, FBI counterterrorism investigators can self-issue such letters to get phone records, portions of credit reports and bank records, simply by certifying that the records are relevant to an investigation. Unlike subpoenas, NSLs do not require probable cause, and at the time obliged the recipient to not discuss the demand with anyone, ever. In contrast, gag orders attached to grand jury subpoenas have expiration dates.
The university, which had readily turned over the records in response to a subpoena, rejected the illegal NSL. Two weeks later, Mueller, testifying before the Senate Judiciary Committee, portrayed the university as intransigent and said the incident showed the FBI needed the power to force the turnover of all sorts of records without having to involve the court system.
What a disgusting example of naked power grabbing by the FBI.