After the checkpoint search, which includes swabbing his luggage to check for explosive residue, he said he was often stopped at the gate before being allowed to fly. He said he assumed that the extra scrutiny was because he had flown to Libya to visit relatives. He also expressed support for protests against Muammar el-Qaddafi in 2011, but the extra scrutiny did not happen until this summer.  "It adds this whole air of suspicion about me to everybody on the plane," he said.  Critics argue that the problem with what the agency calls an "intelligence-driven, risk-based analysis" of passenger data is that secret computer rules, not humans, make these determinations. Civil liberties groups have questioned whether the agency has the legal authority to make these assessments, which the T.S.A. has claimed in Federal Register notices and privacy disclosures about the initiative. Privacy advocates have also disputed whether computer algorithms can accurately predict terrorist intent.  The airline industry has supported the expansion of PreCheck and using data about travelers to decide who should receive more or less scrutiny at checkpoints, to reduce security bottlenecks and focus resources on higher-risk passengers.  At the heart of the expanded effort is a database called the Automated Targeting System, which is maintained by the Department of Homeland Security and screens travelers entering the United States.  Data in the Automated Targeting System is used to decide who is placed on the no-fly list — thousands of people the United States government has banned from flying — and the selectee list, an unknown number of travelers who are required to undergo more in-depth screening, like Mr. Darrat. The T.S.A. also maintains a PreCheck disqualification list, tracking people accused of violating security regulations, including disputes with checkpoint or airline staff members.  (Read more: These stocks should weather DC's next storm: Pros)  Much of this personal data is widely shared within the Department of Homeland Security and with other government agencies. Privacy notices for these databases note that the information may be shared with federal, state and local authorities; foreign governments; law enforcement and intelligence agencies — and in some cases, private companies for purposes unrelated to security or travel.  For instance, an update about the T.S.A.'s Transportation Security Enforcement Record System, which contains information about travelers accused of "violations or potential violations" of security regulations, warns that the records may be shared with "a debt collection agency for the purpose of debt collection."  A recent privacy notice about PreCheck notes that fingerprints submitted by people who apply for the program will be used by the F.B.I. to check its unsolved crimes database.  "The average person doesn't understand how much intelligence-driven matching is going on and how this could be accessed for other purposes," said Khaliah Barnes, a lawyer with the Electronic Privacy Information Center, which has fought to block these initiatives. "There's no meaningful oversight, transparency or accountability."  For travelers who feel they have been wrongly placed on some type of watch list or experienced security screening problems, the Department of Homeland Security has established a Traveler Redress Inquiry Program. According to a review by the department's Privacy Office, there were at least 13,000 inquiries to the redress program in the nine months ending March 31, but civil liberties groups and some travelers described the redress process as a black hole.  "A lot of people I know have tried it," Mr. Darrat said. "And it just doesn't really make a difference."  —By Susan Stellin of The New York Times
The Transportation Security Administration (TSA) now runs background checks on you from the moment you buy your plane ticket. NYT reports.