sbm12

Yes, there were. Many years ago when the FARs were drafted they were done with the concept of "unless otherwise permitted." This essentially means that everything is prohibited unless a specific study is conducted and a specific exception (STC) is issued. It prevents the aircraft manufacturers from having to conduct significant amounts of testing for FAA certifications, even if they already know that there likely is no impact on the flight systems. We've already seen this happen several times for in-flight WiFi providers, for example.

And outside of the USA we've seen commercial carriers implement GSM transponders in their planes, essentially demonstrating that it is possible to operate such devices on airplanes in a licensed manner and not have planes falling out of the skies.