Who Should Manipulate The Spine?
SOURCE: World Health Organization
The World Health Organization (WHO) recently crafted and published the WHO Guidelines on Basic Training and Safety in Chiropractic (FULL TEXT Adobe Acrobat 512KB) in consultation with the World Federation of Chiropractic, the Association of Chiropractic Colleges, and various other chiropractic, medical, and osteopathic groups. 
The Guidelines clarify that chiropractic is a separate profession rather than a set of techniques that can be learned in short courses by other health professionals. They also make it clear that medical doctors and other health professionals, in countries where the practice of chiropractic is not regulated by law, should undergo extensive training to re-qualify as chiropractors before claiming to offer chiropractic services. In some countries there have been recent efforts by medical groups to provide short courses of approximately 200 hours in chiropractic technique. The WHO feels this is a bad decision.
The World Health Organization guidelines indicate that a medical graduate should a require an additional minimum of 1800 class hours, including 1000 hours of supervised clinical training, before claiming to offer chiropractic services. 
http://www.who.int/medicines/areas/traditional/Chiro-Guidelines.pdf (Adobe Acrobat file)