1) Public reaction test 2) Test of public opinion 3) Transport to the courthouse 
A trial balloon is information sent out to the media in order to observe the reaction of an audience. It can be used by companies sending out press releases to judge reaction by customers, or it can be used by politicians who deliberately leak information on a policy change under consideration. In politics trial balloons often take the form of an ...
[n] - a test of public opinion 2. [n] - a balloon sent up to test air currents
noun a balloon sent up to test air currents