Five lawmakers were injured early Wednesday in the fight that broke out as opposition leaders tried to delay a debate on the legislation.
The government says the measures to give police heightened powers to break up demonstrations are aimed at preventing violence such as the deadly clashes that broke out last year between Kurds, supporters of an Islamist group and police. Critics say that the new measures are part of a steady march toward blocking mass demonstrations that threaten Erdogan's iron grip over Turkish politics.
The bill would expand police rights to use firearms, allow them to search people or vehicles without a court order and detain people for up to 48 hours without prosecutor authorization. Police would also be permitted to use firearms against demonstrators who hurl Molotov cocktails. Demonstrators who cover their faces with masks or scarves during violent demonstrations could face four years in prison.
Crucially, the measures would give governors — not just prosecutors and judges — the right to order arrests.
In defending the bill, Erdogan said it was "aimed at protecting social order and social peace." Prime Minister Ahmet Davutoglu dismissed accusations that the measures will violate civil liberties, saying the goal is to protect society: "No one will be able to demonstrate with Molotov cocktails," he said over the weekend.
Metin Feyzioglu, the head of the Turkish Bar Association, said that giving local governors even limited powers to order arrests without going court orders is tantamount to martial law. "This is an extremely dangerous development," he said.
In recent years, Turkey has curbed media freedoms, cracked down on critical social media postings and prosecuted hundreds of people who took part in violent mass protests against the government in 2013 that centered on Istanbul's Taksim Gezi Square. In one case, Turkish prosecutors are seeking possible jail time for a former television presenter who posted a tweet suggesting a cover-up in a government corruption scandal. A Turkish schoolboy was also charged for publicly criticizing Erdogan over the scandal — falling afoul of a law against insulting the president.
"Erdogan is aware that he is not going to be able to achieve his goals through purely democratic means," said Gareth Jenkins, an Istanbul-based analyst with the Institute for Security and Development Policy. "If you are trying to stop people from expressing their opinions, it is a sign that you are not accountable."
The government has even extended its crackdown to sporting events, mindful of the outsized role that soccer fans from some Istanbul professional teams played in the Gezi protests. Prosecutors are seeking life sentences for dozens of fans from one club, Besiktas, on charges that they helped organize the protests as part of a coup.
Under regulations that went into effect last year, fans are required to register personal details in advance, including their government ID number and preferred team, before they can buy a ticket. The government says that the regulations, which were written before the protests, are solely aimed at preventing hooliganism — but fans are suspicious of such claims.
"There is the perception that the aim is to keep track of people," said Bagis Erten, a sports analyst and production manager of Eurosport Turkey.
The government says that the new security law was crafted to conform to European norms. But the Council of Europe's commissioner for human rights criticized the bill, saying that it increased the likelihood of police human rights violations.
"I therefore urge the Turkish Parliament to reconsider the current proposals in the light of relevant international standards," Nils Muiznieks said in a statement.
Opposition parties have vowed to obstruct the bill by submitting hundreds of proposed amendments. The beginning of debate was scheduled for Tuesday, but after hours of delay, fighting broke out during a closed-door session after opposition parties submitted several unrelated motions in their bid to hamper the bill.
Lawmakers threw chairs and two legislators were hit with the gavel. Two legislators were hospitalized, with three others treated in the parliamentary infirmary.
Kurdish lawmakers say they fear the new measures could be aimed at repressing Kurdish demonstrators. If passed, they warn it could jeopardize ongoing peace talks between the government and a Kurdish militant group.
"We will do all in our power to stop the bill," said pro-Kurdish party leader Selahattin Demirtas. "We will act together with all opposition legislators and cause a gridlock in parliament that will last for months."
But few believe the opposition effort will succeed: Erdogan's ruling Justice and Development Party has a strong majority in Parliament — and is likely to eventually find a way to ram through the bill.
Butler reported from Istanbul.
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