The police are probably the only group in Hong Kong who think Sunday's chaotic rally was not political. Of course it was political. When you have pro-establishment and anti-government factions fighting each other, you can't get any more political.
It's true the rally was supposed to be in support of the police because the main organising group was responding to the row over teacher Alpais Lam Wai-sze, who hurled abuse at officers last month. She was upset about perceived bias in their handling of a confrontation between the Falun Gong religious movement and a pro-government group.
To be sure, when everything is politicised, it makes the job of policing much more difficult and complicated. But this is all the more reason for police to stick to the most basic principles by which officers must abide to do their job; and not allow themselves to be drawn into disputes. One of these is to stay out of politics.
Did Lam interfere with police work? If so, she should have been arrested. It was not for the police or police unions to denounce her afterwards for acting inappropriately. Officers enforce the law, not moral or social norms.
Police officers on Sunday acted with professionalism in keeping the peace. They are to be commended. But the police statement appears to have been issued solely in support of retiring superintendant Gregory Lau Tat-keun, who took part in the rally when there are explicit rules in the police guidebook against participating in political functions, parties and rallies. In fact, the statement already contains an excellent argument defending Lau's right to take part in the rally without the need to judge whether it was political or not. Officers on pre-retirement leave, it says, are not authorised to discharge constabulary duties, so their views and deeds will not interfere with the impartial discharge of police duties anyway.
However, even more dangerous is that Chief Executive Leung Chun-ying and Chief Secretary Carrie Lam Cheng Yuet-ngor appear to have endorsed the police's position. If Sunday's rally was not political, then many future rallies could be deemed non-political too. It's open season for police officers to join them. Unless police want to invite controversy, that's a route to avoid at all costs.