‘Obstructing a police officer’ is used as a generalised threat against peaceful protesters
The offence of Obstructing a police officer was surely intended by parliament to prevent people from actively and physically blocking police officers from conducting their duty, such as in making an arrest.
However, this offence (in addition to the common law right of police officers to arrest people to prevent a breach of the peace) is being used routinely against legitimate protesters, and the offence really translates as 'refusing to do what a police officer tells you to do'. Often you hear officers at peaceful protests saying 'move or you'll be arrested for obstruction' for most people this works as they don't really want to risk being arrested – it's too often used a deafult threat to enforce the will of officers on members of he public
This is compunded because if you are arrested and charged with obstruction its almost impossible to be acquitted by a magistrate – if an officer says he was obstructed from conducting his/her duty then they usually accept this.
Why does this idea matter?
This fosters the belief among police officers that they ARE the law in a general sense rather than upholders of specific laws passed by parliament, they think they are in charge and you must do what they say or you are comitting an offence, and no explanation is needed.
in a case i was involved in i have heard police officers say 'people usually do what i tell them to do, they don't need a reason' – this kind of attitude makes anyone on the receiving end lose all respect for the police as a public service
– a tightening of the definition of 'obstruction' and an explicit recognition in the statute that simply not doing what an officer tell you to do is insufficient.
– an reminder to police officers that people can do whatever they want to do unless it breaches specific laws, and it is in fact a duty of police to facilitate everything
– an explicit duty on police officers to explain what offence someone could be arrested on suspicion of if they threaten or suggest that someone could be arrested