Good point.  Did a real quick check on the IRS web-site Pub-15 and came up with this.

Independent Contractors 
People such as lawyers, contractors, subcontractors, and auctioneers who follow an independent trade, business, or profession in which they offer their services to the public, and generally not employees.  However, whether such people are employees or independent contractors depends on the facts in each case.  The general rule is that an individual is an independent contractor if you, the person for whom the services are performed, have the right to control or direct on the result of the work and not the means and methods of accomplishing the result.

    I will have to do some more digging later on.
     Jay