If music be 'sounds wholly or predominantly characterised by the emission of a succession of repetitive beats', play on.

Repetitive Beat Syndrome - that collection of symptoms newly identified by the Home Office as the sound of subversive rave music - comes under scrutiny this week when Autechre (below) unveil a track called 'Flutter' on the group's new EP, Anti. What the band is anti is the Criminal Justice Bill, which seeks, among other things, to curtail the right of groups of more than 10 people to congregate and play such 'music' on 'any land in the open air' which is unlicensed. Autechre has decided to fight the power by releasing a track with a constantly changing rhythm. The High Court will have a hair-splitting time deciding if this falls under the definition. The band's Sean Booth explains: 'We made as many different bars as we could on the drum machine, then strung them all together. Contrary to what's normal, the beat is ever-changing, but the melody is simple and repetitive, so you know where you are. It sounds very strange.'

All this would be pretty academic if it were not for the fact that Autechre is one of the better experimental industrial techno acts to have come up through the traveller rave scene. As the album Incunabula and single 'Bass Cadet' were both number ones in the indie charts, they're in line for radio play. Londoners have the chance to hear the theory in practice on Sunday 24 July when the track will be previewed at a Socialist Worker's Party-run march which leaves Hyde Park at 1pm for Trafalgar Square. All the usual ravers will be there - Tony Benn, Bernie Grant, Arthur Scargill - plus mobile sound systems heading on to parties later in the day.

The only questions are, how do you dance to it, and does this mean people will soon be sticking on Steve Reich's Different Drumming at the patio barbecue?

There will be a benefit for Liberty (071-403 3888) the anti-Criminal Justice Bill organisation, on 21 Jul at Turnmills, EC1 (071-250 3409)

(Photograph omitted)