The following is a guest post from H.L. Pohlman, the author of “Terrorism and the Constitution” and the A. Lee Fritschler Professor of Public Policy at Dickinson College.

Last week the House Rules Committee took a page from the original passage of the Patriot Act in 2001 when it revised a draft of the USA Freedom Act unanimously endorsed by two House committees. On Thursday, with a closed rule to aid it on its way, the bill passed the House by a wide margin.

The leadership’s changes, however, were not well received by civil libertarians. Four key changes suggest why.

Their first concern, and the one most widely noted, is with the new definition of the kinds of “specific selection terms” that the National Security Agency (NSA) could use when applying for court orders for the production of call detail records from private phone companies. What will NSA be searching for? The bill endorsed by the two committees defined “specific selection term” as one “used to uniquely describe a person, entity, or account.”  The revised bill defines it as “a discrete term, such as a term specifically identifying a person, entity, account, address, or device, used by the Government to limit the scope of the information or tangible things sought pursuant to the statute authorizing the provision of such information or tangible things to the Government.”

The new definition is obviously far more open-ended — indeed, the entirety of the original meaning is now only illustrative of the wider possibilities. The operative phrase is “a discrete term . . . used by the Government.”  Given the dictionary definition of “discrete” (apart or detached from others; separate; distinct) this suggests all terms not combined with others — indeed, any term that does not encompass the complete universe of the type of “tangible things” that the government is seeking — would qualify as a “specific selection term.”

Second, the revised bill abandons the earlier bill’s requirement that all call detail records be destroyed after five years unless they are relevant to an ongoing terrorist investigation. The new version only requires the “prompt” destruction of call records. Further, it changes the default rule by requiring destruction only if the government determines that the call records “are not foreign intelligence information.”  How many such records will NSA determine have no foreign intelligence value?

Third, the old version of the bill prohibited the dissemination of non-publicly available information if it “identifies any United States person, without such person’s consent, unless such person’s identity is necessary to understand foreign intelligence information or assess its importance” or “is evidence of a crime.”  The new version only admonishes the attorney general to adopt “privacy procedures” that shall “to the maximum extent practicable and consistent with the need to protect national security, include protection for the collection, retention, and use of information” concerning such a person.  Those privacy procedures are themselves likely to be classified.

Finally, the bill may actually give NSA a kind of backdoor authority to collect telephone call detail records.  The earlier bill carved out the government’s authority to obtain call detail records from its more general ability to obtain “tangible things” under the Patriot Act’s so-called business records provision. It required that the investigation be linked to international terrorism, as well as flowing from a “reasonable articulable suspicion” that the government’s “specific selection term” was “associated with a foreign power or an agent of a foreign power.”

The new version adds broader approval for such searches in a crafty parenthesis: “(including an application for the production of call detail records other than in the manner described…)” Since the manner described refers specifically to “the production on a daily basis of call detail records,” what if the NSA sought instead to do this weekly? Monthly? Is that a different “manner” and thus outside the limits noted above? If so, then the revised bill would basically allow the NSA to continue to obtain telephone call detail records with even fewer restrictions than in the past.

As usual, then, the devil is in the details. Vagueness is certainly a plus for the administration. Indeed, a cynical interpretation of all this suggests that those who crafted the new USA Freedom Act want to give the illusion of reform while preserving (even extending) the NSA’s current activities behind a fog of legalese. Rep. James Sensenbrenner recently said of the act: “The N.S.A. might still be watching us — but now we can be watching them.” But further drafts, as the bill moves to the Senate, will require careful surveillance.