In the run-up to the West Bengal assembly election in 2011, the Trinamool Congress Party's Mamata Banerjee promised poriborton or change from the ills of the ruling Left Front government, which had been in power for 34 years in a row. Chief among these ills, she alleged, was the use of violence by the Communist Party of India (Marxist), the coalition government's main constituent, against members of the opposition.

Just three years after Banerjee's party swept to power in that election, we see little poriborton. In the latest incident, regional TV channels earlier this week aired video footage showing Tapas Pal, a TMC parliamentarian, threatening opposition members with rape and murder during a rally last month in his constituency in the state's Nadia district.

When Pal's statements became public, they evoked so much outrage that the TMC was forced to ask him to apologise. Yet even in a climate when the media and civil society are more alert than before to threats of violence against women, after the horrifying Delhi gangrape in 2012, Banerjee is not pressing for Pal's arrest and is blaming the TV channels for targeting her party members.

This is a pattern. Several TMC leaders have made egregious statements in public, ones that could attract provisions of India's criminal laws relating to threats of violence, murder and rape, but the government has not acted against any of these politicians.

Take the case of Anubrata Mandal, who heads the party in Birbhum district and against whom there is a police complaint about the murder of an independent candidate. A year ago, he incited fellow workers to burn down the houses of independent candidates and bomb police officers if they dared to interfere. In November, he publicly threatened to chop off Congress supporters' hands.

Then, while campaigning before the general election earlier this year, Mandal told a reporter that he might just die in an accident if his channel continued portraying Mandal in bad light. These are merely three examples from the past year.

This April, the Kolkata High Court strongly criticised the Bengal government for not taking action against Mandal. "Is this not a cognisable offence?" asked Dipankar Datta, referring to Mandal's threats to the police. "Why didn't the police take steps against the politician who openly asked a mob to hurl bombs on the police? If a politician, who is not even an MLA or an MP, considers himself to be above the law, then I have also taken oath to protect law. There is a limit to everything."

But even after this, Banerjee has not taken action against Mandal, whom she publicly calls by his nickname, Kesto. “Kesto is an efficient organiser, and our party recognizes good and efficient organisers,” Banerjee said in a political rally in Durgapur in February, vowing “to defend him to the end.”

Monirul Islam, a TMC state legislator, is another example. His name appears in a police complaint about the murder of three CPM activists during an altercation at a village meeting. He also admitted on camera that he had "crushed those people under his feet" but his name was not on the charge-sheet. In June 2013, he openly threatened to behead Birbhum Congress leader Bapi Datta. Far from taking action, Banerjee subsequently shared the dais with him several times.

CPM leaders also made anti-women remarks. But at least the party distanced itself from its workers' worst excesses, such as the rape and murder of an activist belonging to the Save Singur Farmland Committee.

The TMC takes pride in having 11 women parliamentarians, the most representing a single state, and that it has a woman at the helm. In practice, its leaders are normalising violence through their failure to take action against a person who has threatened to use rape as political revenge, language that in recent history is unprecedented even in the state's most bitter political battles.