14 CFR 107.19 C:
The remote pilot in command must ensure that the small unmanned aircraft will pose no undue hazard to other people, other aircraft, or other property in the event of a loss of control of the small unmanned aircraft for any reason.
14 CFR 107.39
No person may operate a small unmanned aircraft over a human being unless—
(a) That human being is directly participating in the operation of the small unmanned aircraft;
(b) That human being is located under a covered structure or inside a stationary vehicle that can provide reasonable protection from a falling small unmanned aircraft; or
(c) The operation meets the requirements of at least one of the operational categories specified in subpart D of this part.