There is a good definition of "obstruction" that can be considered when looking at Sec 89(2) of the Police Act 1996, where the offence that the chap was found guilty of is laid out:
"‘Obstruction’ includes any intentional interference, e.g. by physical force, threats, telling lies or giving misleading information, refusing to cooperate in removing an obstruction, or
warning a person who has committed a crime so that he can escape detection (e.g. keeping lookout for a street game)."
Almost identical is the definition found in the Oxford Law Dictionary, but this uses an illustration related to this story:
"“Obstruction” includes any intentional interference, e.g. by physical force, threats, telling lies or giving misleading information, refusing to cooperate in removing an obstruction, or
warning a person who has committed a crime so that he can escape detection (e.g. warning a speeding driver that there is a police trap ahead)."
So it is a prosecutable offence.
However, you do have to question the wisdom of following this through and the negative reflection it places on the police. On the other hand, it would seem that the chap was his own worse enemy - seemingly "questioning" the officer at the time, having no legal representation, and having been in front of the court before (presumably about the same offence) as the picture caption suggests.
Perverting the course of justice has a clear definition in law - one or more of three things has to be proven to have taken place:
1. Intimidating or threatening a case witness or juror
2. Intimidating or threatening a judge
3. Disposing of or fabricating of evidence
Conspiracy is a very difficult concept but again the legislation does lay down clear rules - there is a real agreement, full knowledge of the offence being conspired, etc. It is not a simple offence to be convicted of.
Thanks to the legal guys I'm working with today