I support the use of body cameras by Police, I believe it will protect officers from unsubstantiated allegations of misbehaviour but also protect the public from officers who do misbehave.
As other have said, buying and operating the cameras will be relatively inexpensive, but managing the enormous volumes of data - all of it potentially evidential and therefore requiring a 100% tamperproof custody trail - would be very expensive.
Working on about 6000 'front-line' police implies about 1200 or so on duty at any time, let's say each camera would generate 100GB per day of footage (mostly of the dashboard of a Police car, very dull) that's 120TB per day, 43Exabytes per annum of Write-Once Read Hardly Ever data. And of course we need a dual-redundant geographically distributed storage solution - I wouldn't mind the sales commission on contract for that!
On the other hand, I remember reading an article about the adoption of body cameras by an English County Police Force, and that it (somewhat unexpectedly) resulted in the number of defended hearings for minor offences dropping to one-third of the previous level. Apparently, once the arrested person and their lawyer looked at the video coverage, the offender rather often put their hands up and pleaded guilty, no more court time wasted with "he said / she said" testimony.
So potentially a big saving in Vote Justice, and a big extra spending in Vote Police.
[fix speling musteaks]