Chiropractors have been successful in preventing PTs from using spinal manipulation by getting state legislation passed barring them from doing so, even though there is not a shred of evidence that PTs are any less capable at it. PTs using their signature treatment scares them, because patients might start using PTs just to avoid the woo-ishness of chiropractic. And, of course, MDs prefer to refer patients to PT, so when manipulation is in order the PT will get the business.