Washington Post 
Thursday, December 30, 2010
A year after a Nigerian man allegedly tried to blow up a Detroit-bound airliner, officials say they have made it easier to add individuals’ names to a terrorist watch list and improved the government’s ability to thwart an attack in the United States.
The failure to put Umar Farouk Abdulmutallab on the watch list  last year renewed concerns that the government’s system to screen out potential terrorists was flawed. Even though Abdulmutallab’s father had told U.S. officials of his son’s radicalization in Yemen, government rules dictated that a single-source tip was insufficient to include a person’s name on the watch list.
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Since then, senior counterterrorism officials say they have altered their criteria so that a single-source tip, as long as it is deemed credible, can lead to a name being placed on the watch list.
The government’s master watch list is one of roughly a dozen lists, or databases, used by counterterrorism officials. Officials have periodically adjusted the criteria used to maintain it .
Full story here.