According to Wikipedia, the Tiahrt Amendment, "prohibits the Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE) from releasing information from its firearms trace database to anyone other than a law enforcement agency or prosecutor in connection with a criminal investigation. Additionally, any data so released is inadmissible in a civil lawsuit."
According to news source, "The Gothamist," this amendment also "requires the FBI to destroy records of gun buyers' background checks within 24 hours." The Gothamist also states that New York Senators Schumer and Gillibrand (Clinton's replacement Senator) are requesting that President Obama eliminate this amendment. This is a turn around for Gillibrand who co-sponsored the bill that created this amendment while she was in Congress.