Lawyerboy
I'm not a lawyer - so please forgive me if I'm butting in on your turf - but I think JPJ may be correct.
The important difference is between Arrestable and Non-Arrestable offences - with an Arrestable offence being either defined as such in the Statute that creates the offence, or any offence carrying a period of imprisonment of, I think, 5 years or more.
Many defendants who will be tried in a Magistrates Court will have been arrested by the Police and brought to Court that way.
For example, in the UK "Drink Driving" is a summary only offence, and can only be tried in a Magistrates Court, but it is an offence for which one is arrested - after failing or refusing the roadside screening test.
As posted above, the likely penalties for a Police Officer who gets it wrong would seem to act as a considerable dis-incentive to swift and robust law enforcement!
[ 13 August 2001: Message edited by: Bellerophon ]