I'm sure it was not illegal to listen, only to act.
In the 1970's I recall a policeman giving a talk at school on police radio equipment, and this subject came up. He said (and obviously this was only a policeman's working knowledge of the law), that if we heard something was on - such as a nearby car chase - and ran out to see the fun, that would be illegal. But to hear it on the radio and do nothing, no offence had been committed.
I believe that this was argued as a defence for radar speed trap detectors some years ago - after many years of summonses and fines, a test case arose where a motorist decided to plead not guilty under the laws at the time, and defended his case on the grounds that his receiver was not equipped to decode the transmission, only to detect that a transmission was taking place; secondly that he believed that the speed trap transmitted no message anyway so he couldn't decode anything even if he wanted to; and thirdly that as soon as he realised that he was receiving signals from police equipment, he switched off his detector (and presumably watched his speed!). He was acquitted. And so a specific law had to be enacted to make the speed trap detectors illegal.
In the 1970's I recall a policeman giving a talk at school on police radio equipment, and this subject came up. He said (and obviously this was only a policeman's working knowledge of the law), that if we heard something was on - such as a nearby car chase - and ran out to see the fun, that would be illegal. But to hear it on the radio and do nothing, no offence had been committed.
I believe that this was argued as a defence for radar speed trap detectors some years ago - after many years of summonses and fines, a test case arose where a motorist decided to plead not guilty under the laws at the time, and defended his case on the grounds that his receiver was not equipped to decode the transmission, only to detect that a transmission was taking place; secondly that he believed that the speed trap transmitted no message anyway so he couldn't decode anything even if he wanted to; and thirdly that as soon as he realised that he was receiving signals from police equipment, he switched off his detector (and presumably watched his speed!). He was acquitted. And so a specific law had to be enacted to make the speed trap detectors illegal.
