(Reuters) - The Turkish parliament is set to begin its second round of voting on constitutional reforms that will make it harder to ban political parties, make the army accountable to civilian courts and overhaul the judiciary.
Here are some of the main reforms and key background:
* The reform would make it harder to ban political parties. The EU has criticised Turkey's political parties law, under which almost 20 parties have been banned since the constitution was adopted in 1982 following a coup. The ruling AK Party itself narrowly survived a court attempt to close it down on the grounds that it contravened the country's secular constitution.
* Under current law, the chief prosecutor can file a case to the Constitutional Court to have a party closed, fined or its members banned from politics. Critics say the law has been used by conservative secularists in the judiciary to overwrite popular support for political parties they deem a threat to the status quo.
* Under the proposed reform, a closure case could only be launched if it is approved first by a parliamentary commission made up of five members from each political party that has a group in parliament (parliamentary groups have a minimum of 20 MPs). The speaker of parliament would chair the commission, which would need to pass the motion by a two-thirds majority.
* Among the most contentious issues is reform of the Supreme Board of Judges and Prosecutors (HSYK), which appoints senior members of courts. The EU has called for reform of the HSYK to ensure its independence, but critics say the AK Party wants to take over the judiciary to push its own agenda.
* The HSYK comprises of five judges, plus the justice minister and his undersecretary. The government wants to expand it to 21 members, who would be chosen by the president, the Constitutional Court, Supreme Court of Appeals, another superior court called the State Council, and the Turkish Justice Academy.
* The HSYK has frequently clashed with the government.
* In a reform that would further curtail the powers of the once-untouchable military, self-appointed guardians of the country's secularism, the government wants to limit the power of military courts by allowing military personnel to be put on trial in civilian courts for crimes committed against the security of the state and the constitutional order.
* Any case brought against the armed forces chief and commanders of the army, navy and air force, and the paramilitary general heading the gendarmerie that is related to their duties would be heard in the Supreme Court.
* Dozens of officers, including retired and serving generals, have been charged in civilian courts in recent weeks in connection with alleged plots to unseat the AK government.
* In January, the Constitutional Court overturned an AK Party-backed law allowing military personnel to be put on trial in civilian courts. The armed forces had warned that the law could open the door to politically motivated trials. The military has ousted four governments in the last 50 years.
* In a separate change to the constitution, the government also wants to end immunity from prosecution for leaders of the 1980 military coup, who engineered the current charter. That coup was led by retired general Kenan Evren, who is now in his 90s and has spent much of his retirement painting portraits and landscapes on the Mediterranean.
* The government also wants to overhaul the Constitutional Court, charged with upholding Turkey's secular constitution, by allowing the president and parliament to pick all their members.
* There are currently 11 sitting members and four substitutes. The president now chooses three members directly, appointing the rest from candidates nominated by civilian and military high courts and the Higher Education Board. Under proposed changes, the bench would be increased to 17, with parliament choosing three members and the president choosing 14.
* Critics say changes would give the president, elected by a popular vote, leeway to dictate the court's direction.
Writing by Ibon Villelabeitia; Editing by Maria Golovnina