Magistrates do not actually side with anybody, Thierry. They form an impartial tribunal that hears evidence from both sides and reaches a verdict based on that evidence. Furthermore, when announcing their verdict, they have to state the reasons for their findings in open court. This, of course, makes their task more onerous than that of a jury who simply have to declare “guilty” or “not guilty”. Your PCSO and Special Constable friends are not best placed to comment on the criminal justice system any more than habitual burglars or drug dealers are.
Your views on the courts’ treatment of domestic violence (which does not, incidentally, always have women as victims) is interesting. Once again, it may be wise for you to do a bit of research into the issue (which might involve studying some of the statistics surrounding such incidents) before making sweeping statements such as “…courts are generally sexist.”; “…the law in regards to domestic violence has gone way to far the other way…” and “… now they convict people on such little evidence”. In particular your last remark is fatuous. Courts cannot convict without evidence. If you have seen any examples at first hand (rather than via your friends) I’d be interested to learn about them
Anyway, enough of that as Magistrates do not need me to defend them. When you have gained a little more experience in life (and perhaps seen Magistrates at work first hand instead of relying on second hand evidence from people who are clearly not impartial) you may think differently.
Violence which takes place in a domestic situation (which the incident you describe did) aggravates the offence but does not make the burden of proof any lower. The Bench must be convinced beyond reasonable doubt of your guilt. Self defence is a statutory defence against Common Assault (which encompasses “Assault by Beating”). If you decide to run that defence you have to convince the Bench that the force you used was necessary, proportional to the threat you faced and that you had no other reasonable alternative. The burden of proof rests with you and you must prove your defence to the lower standard “on the balance of probabilities” (i.e that it was more likely to be true than not).
I’m sure your solicitor will have explained all this to you but if you want some more information this might help:
http://www.cps.gov.uk/legal/s_to_u/self_defence/
It is the Crown Prosecution Services guidance to prosecutors that they use when considering a case where self-defence is being claimed.