At least 591 people died in police custody in India between 2010 and 2015, according to a report by Human Rights Watch (HRW).
The report published on Monday, "Bound by Brotherhood", accuses Indian authorities of failing to hold officers responsible for the deaths and of failing to implement accountability mechanisms, that are already in place.
"While investigations were ordered by courts, human rights commissions, or other authorities in some cases, Human Rights Watch is not aware of a single case in which a police official was convicted for a custodial death between 2010 and 2015," said the report, which added that "torture is likely" almost as soon as a person is taken into custody.
While torture is illegal in India, the report said that many were beaten to extract confessions, with the families of the victims often being bullied into silence.
Al Jazeera made several attempts to contact numerous police officials as well as the interior ministry but was unable to reach anyone for comment.
Meenakshi Ganguly, HRW's South Asia director, told Al Jazeera that India's policies to "protect people in custody" are bypased.
"The Supreme Court has had several important rulings. The National Human Rights Commission has set up regulations, the government has put in policy, and yet we find that repeatedly the police just bypass these procedures," said Ganguly.
"They [police] are not held to account when they do so, and when these abuses happen, then it's worse, because when there is torture, when there is death in custody, then unfortunately the entire police force colludes to protect their colleagues," she said.
'Riddled with problems'
Responses to the report from police departments, Ganguly added, were mixed.
"Until you use [the] third degree against them [prisoners], they will not speak," Jairaj Sharma, a retired police officer in the northern Uttar Pradesh state, told the Associated Press news agency.
The "third degree" is a term Indian police use to describe forceful tactics that can range from slapping to severe beatings.
Others called for better practice.
Vikram Singh, a retired Indian police officer, acknowledged that the country’s criminal justice system is riddled with problems.
"My feeling is that not many cases [against police officials] have been registered, not many police officers suspended, and certainly no one has been dismissed in recent years for being brutal on accused and wanted criminals," said Singh.
Colin Gonsalves, senior advocate to the Supreme Court, said that "the number of people dying [in custody] is grossly underestimated - but that's a pretty shocking figure in itself".
"As far as the non-prosecution of police officers is concerned, that is absolutely right," said Gonsalves, who also founded the Human Rights Law Network.
"It's a basic licence to beat the people - the government, the politicians, the ministers, all allow police to beat at will ... they beat any suspect. They may get information, they may not. They beat you because that's the way any investigation goes on in this country," he said.