Sooner or later every serious protest movement is forced to confront the question of the police. Environmental activism has taken some big steps forward in recent months, with the emerging consensus being that the time for polite lobbying is over: climate action needs to be fought for on the streets.

But the police will not simply stand aside and allow this, as was made clear at a recent Extinction Rebellion bridge block action in Melbourne. Dozens of armed riot police were mobilised to intimidate the crowd, including a gratuitous display of cops in military boats patrolling the Yarra River. They surrounded protesters on the bridge, preventing supporters from getting to the demonstration, and arrested more than 40 protesters.

Despite this repression, many prominent Extinction Rebellion activists in Victoria argue that the police must be respected and celebrated for their role in our protests. A debate has ensued, echoing similar debates that have occurred in the UK.

Some argue the debate is merely tactical. But all tactics are underpinned by politics. Socialists oppose celebrating the police because we recognise the reactionary role they play in relation to political movements and in broader society. They are the brutal enforcers of the capitalist system.

In Australia, Indigenous people are at the front line of this brutality. Australian Indigenous people are proportionally the most incarcerated population in the world. They also regularly die in custody. Yorta Yorta woman Tanya Day is just the latest victim; the 55-year-old was arrested while sleeping on a train and then dumped in a cell, where she died hours later.

Aboriginal people are not over-represented in jails because they break more laws. They are over-represented because they are over-policed and their communities deprived of basic resources, funding and cultural autonomy. Police are the most direct enforcers of this systematic racism.

Being African or Muslim today in Australia also puts you at serious risk of police brutality. Whenever the politicians and their media cheer squad pursue a new scapegoat, the police are given the green light to target accordingly.

Under capitalism, real crime goes on every day. Poverty, homelessness, war and climate change are all the product of the decisions made by a tiny minority. But the police will never round up these criminals from their board rooms and mansions and dump them in cells to die.

In addition to imposing and enforcing the unequal status quo, the police exist to prevent resistance to it. The modern police force was formed for exactly this reason. The development of capitalism required an ever larger working class to labour in its factories and mines. This new class, unaccustomed to the indignities of waged labour and concentrated in large numbers in major cities, had a collective interest in and propensity towards challenging the system. The ruling class saw a need to create a specially paid force that could dispel large rebellious crowds and protect private property.

The police still play this role today. They are deployed to make sure the exercise of democratic rights has as little impact on capitalist business as possible, and sometimes to prevent it altogether. Sometimes their presence is barely felt, such as at the enormous climate strikes. At other times they use open repression, as at the recent Melbourne bridge block.

When protest movements become more disruptive and more effective, the police move from intimidation to outright violence. We saw this in response to the Occupy movement in 2011, and we see it currently in Hong Kong, where demonstrations are attacked with tear gas and rubber bullets, and individual protesters are beaten viciously by gangs of police.

The violent history of police in every country in response to the mass democratic occupation of public streets is matched only by their keen defence of the private property of bosses. Despite disputes between bosses and workers ostensibly consisting of opposing groups of citizens, police rarely intervene on behalf of workers. Instead they enforce anti-worker laws and facilitate the use of scab labour.

The police primarily exist as an institution to defend the current order. As within any institution, it is made up of individuals. But it is wrong to see the police primarily as individuals “just doing their job”. Most jobs in a capitalist economy are immoral or compromising in some way. But there is something particularly corrupting about policing. The force stands apart from ordinary people in order to control and intimidate them, sometimes violently. This requires a degree of callousness that is not required of teachers, health workers or most other jobs. As such, there are high levels of racism, sexism and other right wing social attitudes among police. Research points to well above average rates of domestic abusers among police, for example.

Those not willing to take part in the brutal day to day behaviour of police, to absorb their prejudices or to engage in the jocular atmosphere of bigotry and bullying, generally do not survive in the force.

This is partly why there are so few examples of groups of police officers collectively defying orders or breaking from their superiors. During serious struggle, the police tend to become more conservative, more violent and more cohered around right wing ideology.

Because of their bad reputation, there has been a concerted campaign to rehabilitate the police’s image over the past 30 years, assisted greatly by their sympathetic portrayal in numerous television dramas. After the Royal Commission into Aboriginal Deaths in Custody, the force pledged to clean up its act and teach officers better “cultural sensitivity”, and they have also changed their approach to other oppressed groups, particularly LGBTI people. But the only result of such “clean-ups” has been the creation of community liaison officers and toothless educational programs. These initiatives have done little to mitigate police brutality, and more often than not have provided police with more opportunities to monitor and gather intelligence about oppressed communities.

Activists have a responsibility to understand the role of the police. Sometimes, police repression helps to build momentum behind political struggles, but we should never endorse such repression because of this. And it is hopelessly naive to believe that the police could be won to our cause because we demonstrate respect and appreciation towards them. Such whimsy is a kick in the face to the many victims of police repression, political and otherwise.