More than 150 Turkish journalists have taken part in a protest against a new penal code which they say could threaten freedom of the press.
Protesters say the new law could mean more journalists are jailed
The marchers - some in handcuffs and gags - marched to Istanbul's main court to highlight fears the law may lead to more arbitrary arrests of journalists.
They called for a delay in introducing the code, due to apply from 1 April.
Passed as part of Turkey's bid to start EU entry talks, the law won praise in Europe for its human rights reforms.
However, the protesters argue the new code contains vague wording which could make it easier for Turkish authorities to crack down on the media.
It may result in "many arbitrary prosecutions... and pack prisons with journalists", press groups said in a letter to Prime Minister Recep Tayyip Erdogan on Wednesday.
They appealed for him to suspend the code's introduction for at least six months, so 20 articles dealing with the press could be amended.
Orhan Erinc, president of the Turkish Journalists' Association, warned the law would restrict both "freedom of speech and the right to report", Turkish news agency Anatolia reports.
"We had relayed our views to the prime minister but they were not really taken into account," Mr Erinc said outside court on Thursday. "We want this law to be changed."
Mr Erinc said the new penal code also reintroduces prison sentences instead of fines for offences such as publishing material deemed obscene.
Jail terms for journalists had been removed from Turkey's press law in reforms last year - but dozens of dissident writers and academics have been jailed in the past.
Although Mr Erdogan's government has pressed forward with human rights reforms, concerns remain over press freedom.
The prime minister was criticised last month for suing a political cartoonist who made fun of him.
Fehmi Koru, a columnist for the Turkish pro-Islamist daily Yeni Safak, told the BBC News website the 20 articles added to the new penal code were a serious setback for press freedom.
"This government, when it was first set up, claimed it would introduce new press laws which would be much more freedom-loving," he said.
"We are trying to urge the government to change these articles in accordance with their promises when they came to power, that our press would be more free."