Whenever I see someone texting or using a cell phone while driving, it makes me crazy. If you must talk, pull over and stop in a safe location. I've often secretly wished for a device which would jam or deactivate the offending instrument.
Well, it turns out that others are thinking along the same lines. Elinor Mills reports at CNET that "A team of do-it-yourself technology gurus is creating a video series that will show you how to hack everyday objects to get more ~ and novel ~ uses out of them .... The video series demonstrates how to create the devices, from showing exactly what parts you need to how to solder them and build the final electronic item .... the videos are open source and will be available online for free. Exploring the technology you use everyday can increase and improve its uses, as well as save millions of electronics from piling up in landfills."
Among the demonstrations are creating a SIM card reader, hacking a pay phone, a GPS jammer or tracker, and wearable devices that block security cameras. AND, a cell phone jammer that fits into a cigarette pack. Since I'm not certain of the legalities of altering devices that fall under the purview of the FCC, I am not recommending that you use one. I do, however, encourage you to educate yourself. Nothing wrong with knowledge.
The CNET article explains each item and its uses nicely. Scroll to the bottom for a brief sample video on the cell phone jammer. Then, follow your judgment and your conscience.