Turkish voters on September 12 will cast ballots on a constitutional referendum that has encouraged the polarization of society, and has taken on the appearance of a vote of confidence in the country's charismatic prime minister.

The referendum falls on the 30th anniversary of the most brutal of the country's three military coups, and the governing Justice and Development Party (AKP) government has cast it as an exorcism of historic demons. "No country has ever managed to join the European Union with a coup constitution", said Egemen Bagis, Chief Negotiator for European Union accession talks, referring to the current charter, pushed through in 1982 by generals. "This is a historic turning point."

Government opponents, meanwhile, see the proposed changes as a ploy by the former Islamist leaders of the AKP to tighten their grip on state institutions.

The majority of the 27 articles that voters will cast a single vote on are uncontroversial, covering issues such as positive discrimination for women, protection of privacy and collective bargaining. The package would also solidify recent legal changes allowing military officers to be tried in civilian courts, and open the way for the leaders of the 1980 coup to be tried.

The controversy stems from proposals that would give the president and parliament a greater say in appointing members of the Constitutional Court and the Supreme Board of Prosecutors and Judges, a state body responsible for appointing, promoting and - if necessary - sacking magistrates.

Turkey's judiciary definitely needs a shake up. A recent study by a leading Istanbul think-tank found nearly three-quarters of judges saw their job as defending the state, with a significant minority deeply skeptical about human rights.

A pillar of Turkey's authoritarian ideology, the judiciary engaged in a highly politicized struggle with the AKP government after 2007, first twisting laws to block its presidential candidate, then coming within a whisker of closing the governing party down for "anti-secular activities."

Yet many Turks who are strongly supportive of a more democratic constitution doubt the proposed changes are the right way to go about reforming it. "The institutions set up [by the 1980 coup leaders] are completely bankrupt, five sizes too small for the Turkey of the 21st century", commented political analyst Soli Ozel. "But this packet merely increases the executive's control over the judiciary, without changing the judiciary's mentality."

The tiny handful of analysts who have not taken sides also question the government's efforts to portray the referendum as a democratic assault on military-imposed authoritarianism. If it were, they ask, why hasn't the government changed other authoritarian relics of the 1982 constitution, such as bodies enabling the executive to appoint university rectors and the board of a media watchdog. Instead, it has packed them with its own supporters.

Notoriously inaccurate in Turkey, opinion polls appear to show "no" votes closing quickly on "yes" votes. Two surveys done in the last week by A&G Research, widely considered the country's most trustworthy pollster, show 51 percent for and 49 percent against, with roughly one in 12  voters still undecided.

Speaking on television on September 9, Prime Minister Recep Tayyip Erdogan admitted the referendum was likely to be a close call. "It is the result which is important, not the percentages," he said.

A&G director Adil Gur thinks Mr Erdogan is partially to blame for the apparent slip in support: "If he had ... concentrated on the contents of the package, he would have done better. But he preferred to roll up his sleeves and deepen existing divisions."

Since campaigning began in early August, all sides have conducted campaigns distinguished by virulent partisanship. On 18 August, for example, Mr. Erdogan publicly berated Turkey's most powerful business lobby for failing to declare its position on the referendum. "Those who are impartial will be eliminated," he said, using a famous slogan from the 1970s, when thousands of young Turks died in street clashes that culminated in military intervention.  On September 7, he told the private television channel NTV that those who vote no "are coup supporters."

Not to be outdone, one Istanbul-based branch of the secular chief opposition party put up posters in late August sarcastically encouraging passers-by to vote "yes" if they wanted "Muslim women to cover up like nuns."

Social divisions are as deep as political divisions. In Izmir, a secular city staunchly opposed to the AKP, locals have begun campaigning to change the name of a street named after a hugely popular pop singer, a local girl, because she declared she would be voting "yes."

Sezen Aksu "has shown herself to be an AKP supporter," Ulug Ilve Yucesoy, a lawyer for the group said September 7.

The referendum increasingly resembles a dry run for general elections due before June 2011, and financial analysts are concerned that a narrow victory for the constitutional package, or a defeat, could encourage the AKP to engage in pork-barrel politics, throwing fiscal restraint to the wind.

A day after one leading liberal columnist commonly quoted in the international press called "no" voters "mentally ill ... half-fossilized bigot[s]," Soli Ozel thinks the most worrying conclusion to be drawn from the referendum is the complete lack, in Turkey, of what he calls "democratic etiquette."