Solargoods's Blog

Since cell phone  jammers actively broadcast radio signals they may or may not be legal to possess or operate based on the specific laws of the area one is in.

Armenia : legal(citation needed)
Australia: illegal to operate, supply or possess
Belgium: illegal to sell, possess and operate (licensed part of the spectrum)
Canada: illegal, except by federal law-enforcement agencies who have obtained approval
People’s Republic of China: Used by the Education government department as a method of thwarting cheating in schools. During major end of year exams, cell phone jammers are used in areas surrounding high schools to prevent students inside from receiving calls or text messages, which may be used for illicit purposes. In some municipalities however, rather than the use of cell phone jammers, mobile signal towers close to schools are temporarily shut down for the duration of the week as exams are in progress.
Czech Republic: illegal.
Denmark: illegal.
Finland: illegal.
France: France legalized cell phone jammers in (movie) theaters and other places with performances in 2004. Abandoned due to complaints regarding emergency calls. Still legally used inside jails.
Germany: illegal, but installation in jails has been proposed.
India: Government, Religious Places, Prisons and Educational Institution use cell phone jammers.
Iran: illegal to operate by civilians but police forces and military. in electronic markets you can find a lot of models, made in China or India and there is no need for license paper (legal to own). In most of the jails, arresting house, libraries and university class-Romes is already using. Also in 2009 protest against election police forces used cell phone and blue-tooth jammers.
Ireland: illegal to operate. Legally used inside prisons by the Irish Prison Service.
Italy: technically not illegal to own, but illegal to operate, since the Italian law specifically prohibits to disturb radio and telephone communications. GSM jammers are however legal to be used in places like hospitals, churches, movie theatres and other places with performances, and other buildings where and when the use of mobile telephones may result in a leak of sensitive information: on such occasions, cell phone jammers are legal as long as their operation doesn’t interfere with electronic medical equipment (such as pace-makers) and allows cell phones to make emergency calls. Tri-Band Jammers are reserved to, and in use with, the police forces and are being experimented in prisons.
Japan: illegal to use, but legal to own. Buying of mobile short range versions is allowed. Use of fixed high output cell phone jammers with long range is illegal, with fines of up to max $250,000USD and/or 5 years in prison.
Mexico: legal inside jails, often used also in churches and hospitals.
New Zealand: legal inside jails.
Norway: illegal to own and operate. The police and the military can use cell phone jammers in situations in which it is necessary.
Pakistan: legal inside banks, often used also in libraries.
Slovakia: illegal.
Switzerland: illegal.
Turkey: illegal. Only the police and the military use cell phone jammers.
Ukraine: legal, planned to be used in schools
United Kingdom: illegal to use, but legal to own. Installation in jails has been proposed
United States: cell phone jammers are used by federal officials under certain circumstances. Privacy rights of property owners may affect the policy and application of law within buildings. Contact the FCC for permit applications and waivers. For radio communications, it is illegal to operate, manufacture, import, or offer for sale, including advertising (Communications Act of 1934). Blocking radio communications in public can carry fines of up to $11,000 or imprisonment of up to one year. The Homeland Security Act of 2002 may overide the Communications Act of 1934.

Read more:

http://en.wikipedia.org/wiki/Mobile_phone_jammer