Remember when the former home secretary Amber Rudd claimed that the Home Office did not have targets for deportations, or later that she was unaware of those targets? Yet, as it has been confirmed this week, not only were there detention and removal targets, but Home Office officials received bonuses for meeting those targets. Inevitably, in such a system, people who were here perfectly legally were detained and some were removed. That is an entirely predictable consequence of a policy that prioritises and incentivises removals.

The author of this terrible policy was not Amber Rudd. It was the prime minister Theresa May, during her time as home secretary. David Cameron had plucked out of the air the arbitrary and nonsensical target of “reducing net migration to the tens of thousands”. But it was May who made this an article of faith, a target that was never met but that allowed and even encouraged a permanent campaign against migrants. It led to the wrongful detention and deportation of our own citizens.

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As the bonuses for deportations show, these were not mistakes or the result of overzealous officialdom. The targets and rewards were government policy, set by ministers. It should not be forgotten that this was the coalition government’s policy, and the UK Statistics Authority has dismissed the Lib Dems’ efforts to deny this.

The draconian Immigration Act 2014 was also brought in under the coalition. There is a clue in the date. This was the legal underpinning to the “hostile environment” policy, which turned teachers, health workers, employers and landlords into snoops and internal border guards.

Although new home secretary Sajid Javid has removed some of the more outlandish aspects of this policy and attempted to rebrand it, make no mistake, the “hostile environment” remains. Some of the recent victims are not from the Caribbean, but elsewhere in the Commonwealth. A number of South Asian residents of this country have been threatened with deportation for the most minor infractions on their tax returns. They have done nothing illegal. They are working here legally, yet they have been told to go.

The brutal summary of the government’s approach came from the prime minister herself, who declared that the policy would be to “deport first, appeal later”.

Whenever the issue of the Windrush scandal has been raised, Ministers have sought to conflate the issue with that of illegal immigration. Naturally, migrants here illegally should be removed. But the Windrush generation, anyone who came here from anywhere in the Commonwealth before 1973, were invited and are here legally. This entire scandal is a natural and wholly foreseeable consequence of this government’s policy, which encourages the assumption that innocent people should be accused of being illegal immigrants. This places the burden of proof on them to prove that they are here legally, rather than the state to prove that they are not. As I and others warned at the time, people would be falsely accused of being illegal immigrants because of their names, their accents and the colour of their skin. This is exactly what has happened.

This is why Labour is committed to ending the hostile environment and overturning the Immigration Act of 2014 that underpins it. We will not be providing bonuses for removals. We will not have numerical targets for deportations either.

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The truth is, you can either have an efficient, fair and humane immigration system that works for all of us, or you can have baseless numerical targets for immigration and deportations. You can’t have both. Numerical targets led to doctors, nurses, engineers and others being refused entry. They also led to our own citizens being deported. Labour pledges to end some of the worst abuses in the system such as indefinite detention, or breaking up families. Labour will also the close houses of horrors that are Yarl’s Wood and Brook House detention centres.

In a speech next month, I will set out Labour’s immigration policy, one which is not rooted in a hostile environment. It will recognise our legal obligations. We want migrants to come here who will benefit us all, whether they are doctors, nurses or seasonal agricultural workers. And when they come, we will treat them and their families with humanity and respect.

• Diane Abbott is the shadow home secretary