By Pam O'Toole
BBC regional analyst
The four were given a hero's welcome in southeastern Turkey
A Turkish appeal court's decision to overturn the convictions of Leyla Zana and three other former Kurdish MPs on charges of links with a Kurdish separatist organisation is likely to be welcomed both by Kurdish human rights groups and by the EU.
The four are to face a retrial.
The case is likely to be regarded as an important symbol of how far the current Turkish government - eager to win a date to start accession talks for EU - has come in democratising the country and improving the lot of its 12 million-strong Kurdish minority.
When Ms Zana and her co-defendants were jailed 10 years ago, Turkey was at the height of a 15-year conflict with a Kurdish separatist organisation the PKK, in which 30,000 people died.
Former PKK leader Ocalan is serving life in prison
Many Kurds were jailed for supporting the PKK, or for making statements regarded as advocating Kurdish separatism.
In 1999, the PKK's leader, Abdullah Ocalan, was arrested; the group announced a unilateral ceasefire and the regional conflict subsided.
But reports of human rights abuses against the Kurdish population persisted, and restrictions on the use of the Kurdish language and cultural rights remained.
The past two years has seen a dramatic shift as the new Turkish government began adopting a swathe of radical democratisation reforms aimed at winning a date to start talks on accession to the EU.
A controversial law used to imprison people for advocating Kurdish separatism has been amended and, for the first time, Ankara has allowed limited Kurdish language broadcasting and education in Kurdish.
Kurdish human rights groups welcome the latest decision on Leyla Zana and her co-defendants as a high profile symbol of how things have started to change.
But they point out that human rights abuses and low scale harassment against people in the largely Kurdish south east continues.
Much still depends, they say, on how quickly and thoroughly the democratisation reforms adopted by Ankara are implemented on the ground around the country.
Meanwhile, Ankara has yet to fully make peace with radical Kurdish groups, offering only a limited amnesty to PKK members and pressurising neighbouring Iraq to take action against remnants of the group in Kurdish areas of northern Iraq.
The PKK, now renamed Kongra Gel, called off the unilateral ceasefire in May this year.
Since then, there's been an upsurge in clashes between Kurdish militants and Turkish government forces in the south east.