In 2000, he stood unsuccessfully as an independent Green Left candidate for the London Assembly.
In 2002, Peter bought an unsuccessful legal action in the British courts for the arrest of the former US Secretary of State, Henry Kissinger, on charges of war crimes in Vietnam and Cambodia during the 1970s.
The same year, he ambushed Mike Tyson outside his gym, just a few days before his world title fight against Lennox Lewis in Memphis, USA. Challenging Tyson over his homophobic slurs against Lewis, Tatchell persuaded Tyson to make a public statement insisting that he was not homophobic and to declare: “I oppose all discrimination against gay people.”
In early March 2003, Tatchell forced Prime Minister Tony Blair’s motorcade to halt in Piccadilly, in a protest against the impending war in Iraq. He ran out into the road and held up a placard opposing invasion and urging instead international aid to the Iraqi people to help them topple Saddam Hussein’s dictatorship. Blair’s car screeched to a standstill just six inches from Tatchell’s legs. Although arrested and detained in Vine Street police station, no charges were pressed.
He participated in the attempted Moscow Gay Pride marches in 2007, in solidarity with Russian LGBT campaigners. Together with others, he was beaten up by neo-Nazis, ultra-nationalists and fundamentalist Christians; sufferingfurther brain and eye damage. The police arrested him, while his attackers were allowed to go free.
In 2009, he co-proposed a UN Global Human Rights Index, to measure and rank the human rights record of every country – with the aim of creating a human rights league table to highlight the best and worst countries and thereby incentivise governments to clean up their record and improve their human rights ranking.
He coordinated the Equal Love campaign in 2010, in a bid to overturn the twin legal bans on same-sex civil marriages and opposite-sex civil partnerships. The following year, he organised four gay couples and four heterosexual couples to file a case in the European Court of Human Rights, arguing that sexual orientation discrimination in civil marriage and civil partnership law is unlawful under Articles 8, 12 and 14 of the European Convention on Human Rights.The case was refused, without explanation contrary to the rules of the ECHR.
In 2011, behind-the-scenes, Peter successfully lobbied the Conservative government to agree the legalisation of same-sex marriage.