Belaid, a leftist politician, had been a fierce critic of Islamist Ennahda party, claiming it turned a blind eye to violence perpetrated by extremists against secularists. He was shot dead in his car by gunmen on Feb. 6, 2013.
Belaid's assassination shocked the country and sparked massive and violent protests at an already turbulent time shortly after the Arab Spring in 2011, when protests erupted first in Tunisia and then across the region toppling several longtime autocrats.
Near Tunis court, dozens of Belaid supporters gathered since Tuesday night, raising slogans demanding justice.
They chanted "Chokri is always alive" and "we are loyal to the blood of the martyrs".
While Belaid had only a modest political following, his criticism of Ennahda policies spoke for many Tunisians who fear religious radicals are bent on snuffing out freedoms won in the first of the revolts that rippled through the Arab world.
Belaid's family and secularist politicians accused Ennahda Islamist party's leaders of being behind the assassination when they were leading the government.
Ennahda deny strongly any connection to the assassination.
Months after Belaid's assassination, Mohamed Brahmi another leftist was shot dead by gunmen also, and mass protests and political pressure forced the Islamist-led government to step down at the time.
(Reporting by Nadine Awadalla, Tala Ramadan and Tarek Amara; Editing by Nadine Awadalla, Kim Coghill and Michael Perry)
