Thefts of smartphones in the U.S. have significantly declined as a result of the introduction of the killswitch. The killswitch makes the phone redundant and can be triggered even when you don't have the phone with you.

Killswitches have been gradually added to smartphones in recent years and have become more and more common. An American consumer research agency reported that in 2014 there was 2.1 million phone thefts and while that seems enormous it was actually a large decline in the activity.

The consumer agency said that the number of thefts across the nation had dropped by 32 percent from the previous year.

This week California will begin implementing a new law that will mean all phones for sale in the state must have a killswitch ability in order to deter crime.

The effect of the killswitch can be seen between Apple and other companies. Apple were among the first to bring in the killswitch and as a result there were significant early declines in the theft of the device over other companies.

George Gascon, the District Attorney in San Francisco, said that the logic behind the killswitch was quite simple.

"This is validation of what we knew to be the case all along, that if you remove the value of a stolen device you remove the incentive to engage in this violent behavior," Gascon said.