The days of simply reading the riot act to an angry crowd are long gone. The Home Office has been investigating the use of high-tech pain rays against mobs as an alternative to the good old water cannon, according to a report by its Scientific Development Branch due to be published next month.

The so-called active denial system (ADS) projects microwave-like radiation for distances of more than 500 yards, creating an excruciating, full-body burning sensation in anyone caught in its beam. The millimetre-wave rays penetrate skin to a depth of about 1/64in but cause no permanent damage, according to Raytheon, the system’s US-based maker. Prototypes of the weapon, called Silent Guardian, weighed about three tons and were mounted on trucks.

“Directed energy systems such as the ADS have seen major advances over the past few years and are likely to continue to do so in the coming years,” the Home Office said. Although the report found “no options that would currently be considered”, it said that might well change in the future. “We’re not saying that the ADS is never going to be used. We’re not going to write it off.”

The Scientific Development Branch, based in Sandridge in Hertfordshire, has been looking at a portable version of the ADS being developed by Raytheon for the US National Institute of Justice – which sounds suspiciously like something from Judge Dredd. The backpack-sized unit is being designed for American police. A working prototype has already been delivered.

The first customer for the full-size active denial system is the US Air Force, which recently published a medical report from Penn State University on the weapon’s effects, in effect clearing it for use in the field. After more than 10,000 test firings on human volunteers, 99% of those exposed to the pain ray agreed that it was an effective deterrent, and only a handful suffered minor blisters. The Human Effects Advisory Panel, an independent body of doctors and physicists, concluded: “The ADS is a nonlethal weapon that has a high probability of effectiveness with a low probability of injury.”

One test the system has not yet passed is that of public acceptability. The idea of firing energy beams at people is likely to meet with widespread concern and this is probably the reason it has not yet been deployed to disperse antiwar protesters. There is also the danger that it could be misused. The weapon is designed to be fired in short bursts of between one and six seconds, at ranges of several hundred yards. When a serviceman was accidentally exposed to a high-power beam at close range, he received second-degree burns requiring skin grafts.

Active denial isn’t the only new technology being considered by UK authorities. The Taser is already in widespread use, and the Association of Chief Police Officers is investigating weapons that utilise laser and kinetic technologies, although it is not clear yet when such devices will be piloted on our streets.

Laser weapons, also called dazzlers, are handheld devices that can temporarily blind criminals, while kinetic technologies include bean-bag rounds, water cannons and even sponge grenades filled with powdered irritant chemicals.

If you think the British bobby is unlikely to swap his truncheon for a pain ray, laser gun or exploding sponge, think again. Dixon of Dock Green, make way for Robocop.