Drones are currently classified by the FAA as "model aircraft" and the FAA has tried and failed to sue a person for flying one commercially [1]. The FAA thought they regulated commercial "model aircraft" in 2007, but it was thrown out in court in 2014. Until the FAA can pass it's newly proposed rules, commercial operation of drones is unregulated (aside from standard safety regulations).
[1] http://www.bloomberg.com/news/articles/2014-03-06/drone-pilo...