He had a key role in the events of the Romanian Revolution of December 1989[1] and in exposing the human rights abuses of the Ceaușescu regime.

According to the Report Armageddon VII of 2004, it is claimed that Mazilu had been dismissed from the management of the Securitate as a result of an attempt to falsify documents relating to a car accident.

[4] The report detailed Ceaușescu's policy of exporting the majority of Romania's food, and lowering living standards to quickly pay off foreign debts.

As a result of Mazilu's critical report of Human Rights in Romania, he was formally fired from the Ministry of Foreign Affairs in 1987 and his diplomatic passport was withdrawn, preventing him from attending UN meetings.

The same day, Mazilu gave a speech at the government building now occupied by the National Salvation Front led by Ion Iliescu detailing his opposition to Communism[8] [7].

[9] Deeply moved, with the face swelled by the blows received, I told the people from where I came and underlined the anti-communist character of the Romanian Revolution.

The FSN proclamation read by Ion Iliescu on 22 December 1989 was written by Dumitru Mazilu with some editing by Silviu Brucan.

Despite this brief cooperation, tensions between Mazilu and Iliescu began as a result of the big tent ideology adopted by the FSN to present a united front against Nicolae Ceaușescu.

These tensions culminated when during a march of remembrance for the fallen of the revolution on 12 January 1990, Mazilu attempted to use the dissatisfaction of the crowd to seize leadership of the FSN from Iliescu.

There was speculation that former Securitate officers were behind the incident; furthermore, it was alleged that this was part of larger campaign of assaults on other journalists and opposition leaders, including the murder of Ioan Petru Culianu.

[citation needed] In the years 1991–1993, Mazilu won a lawsuit filed by the Romanian authorities regarding his improper firing from the Ministry of Foreign Affairs during the Ceaușescu regime.

In December 2004 – the 15th anniversary of the revolution – there was a symbolic reconciliation between Mazilu and Iliescu, who with his cabinet had since adopted social democracy, thus quelling earlier ideological tensions between the two.

In November 2013, Mazilu was interviewed in the General Prosecutor's Office as a further investigation of the events of 1989 in light of accusations surrounding Iliescu.

The following year, Mazilu testified against Iliescu, stating "I am certain now that revolutions are conceived by idealists, enacted by fighters and taken advantage of by opportunists".

In 2002, he received the International order "Science – Education – Culture", Commander rank, awarded by the European information Academy.

In recognition of his contribution to the defense of human rights during the years of the communist dictatorship in Romania, Mazilu was nominated for the Nobel Peace Prize by the International Diplomatic Academy in 2003.