The Posse Comitatus Act has traditionally been viewed as a major barrier to the use of U.S. military forces in planning for homeland defense. In fact, many in uniform believe that the act precludes the use of U.S. military assets in domestic security operations in any but the most extraordinary situations. As is often the case, reality bears little resemblance to the myth for homeland defense planners. Through a gradual erosion of the act’s prohibitions over the past 20 years, posse comitatus today is more of a procedural formality than an actual impediment to the use of U.S. military forces in homeland defense.
Click here for the rest of the article.
UPDATE written by the author of the above article -- "Resurrecting Posse Comitatus in the Post-9/11 World"
Additional blog posts on Posse Comitatus by clicking on this sentence.