It was disturbing to learn the other day just how close the last administration came to violating laws barring the military from engaging in law enforcement when President George W. Bush considered sending troops into a Buffalo suburb in 2002 to arrest terrorism suspects. Unfortunately, this is not necessarily a problem of the past. More needs to be done to ensure that the military is not illegally deployed in this country.

The Posse Comitatus Act of 1878 generally prohibits the military from law enforcement activities within the United States. If armed officers are going to knock on Americans’ doors, or arrest them in the streets, they should answer to civilian authorities.

Despite this bedrock principle, The Times’s Mark Mazzetti and David Johnston reported last week, top Bush administration officials, including (no surprise) Vice President Dick Cheney, argued that the president had the authority to use the military to round up a suspected terrorist cell known as the Lackawanna Six.

Mr. Cheney and others cited a legal memorandum co-written by John C. Yoo (author of the infamous torture memo), which made the baseless claim that the military can go after accused Al Qaeda terrorists on United States soil because it would be a matter of national security, not law enforcement.