If former New York mayor and Democratic presidential candidate Mike Bloomberg was missing from action in the Iowa caucuses and the New Hampshire primary, his campaign has been attracting significant attention elsewhere, including in southern states where black voters have decisive electoral power.

He has been endorsed by several black mayors, polled at 15 per cent support nationally and has been endorsed by a handful of swing district members of Congress.

But Bloomberg’s play for black voters may have hit a hurdle: his record on policing. In a recently resurfaced video, Bloomberg is heard explaining his “stop, question and frisk” policies at a 2015 Aspen Institute event. Bloomberg states that “95 per cent of your murders — murderers and murder victims fit one M.O. You can just take the description, Xerox it and pass it out to all the cops. They are male, minorities, 16 to 25. ... The way you get the guns out of the children’ hands is to throw them up against the walls and frisk them.”

His remarks seemed to suggest that profiling and harassing young black and Latino men was OK.

Bloomberg has recently apologised for the programme. But for a candidate telling voters he has the “record and the resources” to win the presidency, an actual look at his record shows that his administration promoted policing tactics that deepened the racial inequality that plagues the US criminal justice system.

Under his tenure as mayor, stop-and-frisk increased dramatically from 97,296 documented cases in 2002 to 685,724 at the height of the practice in 2011. His 2015 remarks suggest that he believed labelling and targeting young black and Latino men as inherently criminal was good policy — but the data shows that that is not true, and the historical record shows the dire consequences that racial profiling has had on black and Latino communities.

Arbitrary stops, harassment and abuse by police in black neighbourhoods across the country were rampant even before the 1960s, and they were a major contributing factor to the nationwide riots of the 1960s. The specific term stop-and-frisk was coined in New York in 1964 when the first law was passed allowing police to stop, interrogate and frisk any person who they believed to be involved in criminal activity and in possession of a weapon — all based on reasonable suspicion, a lower standard than the probable cause demanded for a search warrant.

And although stop-and-frisk was never limited to New York — Terry v Ohio in 1968 was a key case in establishing legal precedent for stop-and-frisk policies — New York was a critical battleground for the practice. In 1968, when New York’s version of stop-and-frisk landed in the Supreme Court, the justices ruled in Sibron v New York and Peters v New York that the practice did not violate constitutional rights.

That green light meant that stop-and-frisk continued in the decades to follow. In the early 1990s, as crime began to drop precipitously in New York after record highs, Rudy Giuliani, as mayor, and police commissioner William Bratton expanded the practice, combining it with a new theory of “broken windows” policing and new technology, notably the CompStat system in 1994. CompStat used new computer technologies to crunch crime data to locate hotspots, or places where alleged crime and criminals were most concentrated. Using data from CompStat, the city argued that it could ramp up stop-and-frisk in hotspot areas.

Asserting that the practice violated their civil rights while failing to make their neighbourhoods safer, however, black communities brought legal challenges against stop-and-frisk. In a 1999 New York class-action lawsuit, a federal judge ruled in a settlement that as a result of the racially disparate impact of the programme, the New York City Police Department must release data on stops quarterly.

When Bloomberg succeeded Giuliani in 2002, he continued to promote the stop-and-frisk programme as a means to reduce crime, and under his tenure, the programme ballooned. Along the way, New York City served as a trendsetter for police departments across the country, such as the one in Newark, where stop-and-frisk rates soared.

Data served as a justification and driver of the programme, and many people today may wonder if the programme simply targeted high-crime areas, as Bloomberg’s remarks seem to suggest.

But the New York Civil Liberties Union showed that the NYPD targeted innocent black and Latino New Yorkers at an alarming rate, and the federal courts agreed in 2013. When a federal judge examined the data, she found that black and Latino people were more likely to be stopped in neighbourhoods across New York, even after controlling for other factors such as reported crime rate. Black people were more likely to be arrested than their white counterparts for the same suspected charge, as well as more likely to be subjected to the use of force.

Moreover, the judge wrote, “the city’s highest officials have turned a blind eye to the evidence that officers are conducting stops in a racially discriminatory manner. In their zeal to defend a policy that they believe to be effective, they have wilfully ignored overwhelming proof that the policy of targeting ‘the right people’ is racially discriminatory and therefore violates the United States Constitution”.

In response to the decision, Bloomberg told The New York Times: “You’re not going to see any change in tactics overnight.”

Faced with the data demonstrating that the policy was unconstitutional, he wanted to allow stop-and-frisk practices to continue through the end of his administration anyway because “I wouldn’t want to be responsible for a lot of people dying”, he said.

But although city and police leaders always argued that the strategies were reducing crime, crime had already begun to drop dramatically after the early 1990s — a phenomenon, known as the great crime decline, which occurred throughout the country. The data also revealed that the programme was a failure; in nearly 99 per cent of the time, no weapon was found. There was also no demonstrated link between stop-and-frisks and New York’s falling crime rate.

But the data does show the deep harms of stop-and-frisk policies. The effects go beyond inconvenience and harassment. Studies showed that young men who lived in neighbourhoods with high stop-and-frisk rates experienced high rates of nervousness, feelings of worthlessness and emotional distress, as well as anxiety and symptoms of post-traumatic stress disorder. Stop-and-frisk also reduced engagement with other city of New York entities, leading communities to avoid reaching out for help from the city via 311 calls.

Bloomberg has targeted black voters for support throughout his presidential campaign, but he only recently apologised, seemingly out of political expediency, for stop-and-frisk after two decades of advocating for the programme.

Some black voters and leaders still continue to support Bloomberg despite this record, including former Philadelphia mayor Michael Nutter.

But the 2015 video reveals that Bloomberg didn’t just increase stop-and-frisk during his time as mayor. He also supported targeting young black and Latino men, citing that they are disproportionately prone to criminality, and that harassing and humiliating large numbers of them was a non-issue as well as a way to make New York a safer place.

He even went as far as saying that the police didn’t stop black and Latino people frequently enough. He made these comments even after the courts had ruled that the programme was unconstitutional. Today in New York, a modified programme continues on a smaller scale — but smaller though it may be, it is still being carried out in a racially disparate way.

As mayor, Bloomberg showed a stunning disregard for the civil and constitutional rights of millions of the city’s residents, rolling back stop-and-frisk reluctantly only as a result of lawsuits. If Bloomberg — or any candidate without a strong commitment to anti-racist polices — becomes president, we have to wonder if he will recognise that the constitutional and civil rights, which the president must swear to uphold, apply to all, including black and Latinx people.

• Philip V. McHarris is a writer and PhD candidate in sociology and African-American studies at Yale University