GoKawiilThe usage of any jammers, Bluetooth included, is illegal in most countries, with minimal exceptions like military applications. In the United States, it is outlawed in the Communications Act of 1934 and further solidified by Federal Communications Commission (FCC) rules. Many other countries have similar legislation, with the International Telecommunication Union, a United Nations agency, outlining several articles for all member countries regarding radio wave interference.
With a myriad of devices running across the 2.4 GHz band, the usage of a jammer affects anything nearby. Even ones designed for close-range personal use can have a range of around 50 feet, which is more than enough to disrupt nearby Wi-Fi, baby monitors, security systems, medical equipment like glucose monitors and much more. Most importantly, it can impact law enforcement and first responders' ability to do their job, as it can interfere with Bluetooth-based communications and body cameras. Stronger jammers can even affect important vehicle equipment that utilizes Wi-Fi, as well as critical services like emergency dispatch networks and remote access to patient medical data.
Not only is it forbidden to use jammers, but their use can be traced due to the fact they broadcast their own location. Through a combination of spectrum analysis tools and direction-finding equipment, law enforcement can track you down, and the consequences will be much more than a slap on the wrist. The Department of Homeland Security encourages citizens to report any suspected jamming, and those found guilty of utilizing signal jammers of any kind can face significant fines and even jail time.