The EU is pushing the United States for answers following reports that the National Security Agency siphoned bank messaging data held in the European Union, possibly in violation of a July 2010 treaty.
Defense attorneys are hoping to overturn convictions against their clients in dozens of money laundering, drug and other cases that they say may have been based on undisclosed national security data.
Lawmakers are scheduled to decide next week whether to extend a Patriot Act subpoena power and to limit the use of a controversial emergency letter used to obtain data on bank customers.
The U.S. Senate Judiciary Committee approved a bill Thursday that would potentially discontinue use of a controversial emergency law enforcement subpoena by 2012.
The FBI has yet to resolve problems with how it uses special subpoena authorities granted under the Patriot Act, according to the U.S. Justice Department's Inspector General.
The subpoenas allow agents to obtain data from institutions for terrorist and spy cases without external vetting.
A federal judge ruled on Wednesday that certain sections of the USA Patriot Act are unconstitutional because they allow law enforcement agents to conduct searches and surveillance without showing probable cause.