Parliamentary career

In 1994 Dittrich became a member of the House of Representatives representing the social liberal party Democrats 66 (D66).

Boris Dittrich rose to become party leader of D66 in 2003 after Thom de Graaf stepped down because of disappointing results in the 2003 general election.

Dittrich negotiated the participation of D66 in the second Balkenende cabinet with the Christian Democratic Appeal and the People's Party for Freedom and Democracy. He decided not to become a minister but to remain party leader in parliament in order to monitor whether the new government would execute the coalition agreement. The new government introduced major reforms to which the staggering Dutch economy responded positively.

Dittrich was strongly against Dutch military participation in the Afghan province of Uruzgan and he tried to persuade the Dutch government and parliament not to get involved in the war. However, when the cabinet (including his own D66 ministers) decided to follow the American lead under President Bush, backed by 75% of the Dutch parliament, he decided to take political responsibility and stepped down as leader of D66 on 3 February 2006. A few months later D66 withdrew its support from the government after three years because of a dispute with Minister for Integration and Asylum Affairs Rita Verdonk about the way she handled the issue of the Dutch passport of Ayaan Hirsi Ali. D66 and the minister had had many clashes before because of her harsh policy towards asylum seekers and immigrants. This withdrawal caused the fall of the government and a snap election was announced for November 2006.

Dittrich was a highly productive parliamentarian; he is the first member ever to have drafted four different private member's bills that have successfully become law. Dittrich took the initiative for laws against stalking; for the rights of victims to speak during a criminal trial; for abolishing the time limits on prosecution of crimes like murder and manslaughter; and he wrote the law to fix book prices in order to protect smaller bookshops, authors and customers.

During his career, Dittrich became a national figure for his initiatives on issues like same-sex marriage, euthanasia, legalization of specific forms of sex work, and decriminalizing the use of soft drugs. These are issues that have made the Netherlands 'leading' when it comes to this kind of legislation in the world. Dittrich was the first openly gay member of parliament who focused on LGBT rights (Evelien Eshuis from the Dutch communist party being the first openly lesbian MP who worked for LGBT rights in the 1980s). In 1994 he proposed to introduce marriage equality to the dismay of the Dutch LGBT organization COC. The group later changed course. Dittrich and two colleagues embarked on a long campaign. In spite of fierce opposition from religious groups, the Netherlands became the first country in the world to introduce marriage equality. He is a strong advocate for human rights and represented the Dutch parliament on numerous occasions at meetings in the United Nations. Dittrich was member of the Parliamentarians for Global Action (PGA) and was also vice president of Liberal International until October 2007.

After twelve and a half years in Parliament, Dittrich decided to work outside national politics. He continued in his role as a member of parliament until the November 2006 general election.

Post-parliamentary career

In early 2007 Dittrich became Advocacy Director of the Lesbian, Gay, Bisexual & Transgender (LGBT) Rights Program at Human Rights Watch in the Headquarters of the non-governmental organization in New York City.

Dittrich worked on different levels to achieve non-discrimination and equal rights for LGBT people. On a national level he supports grass roots organizations to achieve the goals they set out in their country specific context. For instance when groups in Cameroon asked Human Rights Watch to research the effects of the law that criminalizes homosexual conduct in that country. The research resulted in a joint report that Dittrich and the groups’ representatives discussed at a national level with the Cameroonian prime minister, minister of Justice, members of Parliament, and other stakeholders. On an international level Dittrich presented the findings from the report on Cameroon to the UN Human Rights Committee in Geneva.

In New York he co-organized yearly events at the United Nations to celebrate International Human Rights Day on December 10. In 2007 he chaired the event that introduced the Yogyakarta Principles to the UN in New York. The 2008 event introduced a joint statement by 66 countries to denounce violence and discrimination against people because of their sexual orientation or gender identity. In 2009 the Holy See took the floor and called upon the more than 76 countries in the world to decriminalize homosexual conduct. The events became increasingly important. In 2010 and 2012 former UN secretary-General Ban Ki Moon gave the opening address. In all events human rights defenders from different parts of the world shared their personal stories about how discriminatory laws and practices influenced their lives. In most cases also positive examples of activism were given to inspire the hundreds of attending diplomats.

Mid 2013 Dittrich moved from New York to Berlin, Germany where he continued to work as global advocacy director of the LGBT Rights Program at Human Rights Watch until October 2018.

Renewed political career

In 2019 Dittrich was elected as senator in the Dutch Senate for his political party D66. His four year term started on June 11.

Decorations

Honours
Ribbon bar	Honour	Country	Date	Comment
	Knight of the Order of Orange-Nassau	Netherlands	29 November 2006