It turns out that the National Security Agency surveillance program uncovered by former government contractor Edward Snowden is just one way in which the government is keeping tabs on us. In the mid 2000s, the Internal Revenue Service's manual detailed a Drug Enforcement Agency program that funneled tips gleaned from overseas NSA intercepts, domestic wiretaps, and informants to other federal agencies to start investigations, Reuters reports. The IRS manual instructed its investigators to scrub any mention of how they got the tips in the first place, essentially covering up the investigative trail. However, the agency removed mention of it in 2007. The practice has been highly criticized by both prosecutors and defense attorneys who say the practice violates the Constitution. The DEA defends its program, saying it is necessary to provide cover for its sources.