RAMALLAH, West Bank — Yousef Shayeb, 37, a Palestinian journalist from Ramallah, published an article in a Jordanian newspaper this year charging officials at the Palestinian diplomatic mission in Paris with corruption and espionage. In an interview here last week, he said that he had imagined people might thank him for his exposé. Instead, he spent eight days in a Palestinian Authority jail.

Jamal Abu Raihan, a Palestinian blogger, has been in prison for three weeks, after he posted a satirical column lampooning the Palestinian president, Mahmoud Abbas, as a donkey on a Facebook page he ran titled, “The people want an end to corruption.”

And in recent months, on the orders of the attorney general, the authorities have tried to block Palestinians’ access to a number of Web sites that officials said were supportive of Muhammad Dahlan, a onetime Gaza security chief and now a rival of Mr. Abbas.

As Palestinian journalists and activists, imbued with the spirit of the Arab Spring, become more daring and enamored with the possibilities of new media and social networking sites, the primary instinct of some in the Palestinian Authority has been to crack down.

Palestinian society, mostly conservative, has traditionally been served by a staid and obedient news media. But the communications revolution has shaken things up.

Now Palestinian officials, journalists and bloggers are struggling to define the principles of freedom of expression and its boundaries, and to distinguish between legitimate criticism and defamation.

“We understand that we have a constructive power,” said Nabhan Khraishi, the communications officer for the Palestinian Journalists Syndicate, “and on the other hand we have a destructive power that can be a catastrophe.”

But even when journalists make mistakes, he said, they should not have been jailed, adding, “We are working to raise the ceiling of the freedom of expression.”

Mr. Abbas, apparently responding to international criticism of the clampdown, issued a statement on Saturday instructing all Palestinian Authority agencies to ensure the freedom of opinion and expression, calling it a “sacred right” based in Palestinian law. He also instructed the attorney general to lift the ban on Web sites, while urging the news media to provide honest and objective coverage.

The journalists’ syndicate has agreed to hold talks with the attorney general and other officials on the detention of journalists and possible amendments to the Palestinian press and communications law of 1995, though most of the detentions appear to have been based on a 1960 Jordanian law.

Amid the brouhaha, Mashhour Abudaka, the authority’s communications minister, resigned April 26, citing personal reasons. Others say he had resigned in disgust.

About two months ago, a disgruntled resident of the West Bank town of Salfit cursed Mr. Abudaka on Facebook and accused him of corruption. Mr. Abudaka filed a complaint with the attorney general to argue for some limits, he said, expecting to meet his accuser in court.

Mr. Abudaka said that the next thing he heard was that the man had been jailed for two weeks.

“I called the attorney general’s office in Salfit and said I did not mean that,” he said. “Two weeks in prison for such a minor offense?” he continued. “I just wanted to make a point. I feel sorry for the guy.”

Mr. Abudaka also condemned the blocking of Web sites, which he said began more than a year ago. In any case, he noted, with Israeli Internet providers covering much of the West Bank, it is impossible to block any site completely, “so why give us the image of a dictatorship?”

Palestinians said it was unclear where the attorney general had been getting his orders from, though he generally answers to the president.

Sabri Saidam, the president’s adviser for communications and information technology, declined to be interviewed, but in a statement to Wafa, the official Palestinian news agency, he said that the blocking of Web sites was both wrong and impractical.

The attorney general, Ahmed al-Mughni, has said that it was necessary to block the sites for security reasons. In an interview with a Ramallah radio station, he also defended the recent detentions.

“We as the attorney general’s office do not persecute people based on their opinions, whether they are bloggers or journalists,” Mr. Mughni told Radio Ajyal, “but when somebody comes to us complaining that someone has defamed him and that he was harmed by the accusation, we have to implement the law. Otherwise how do you protect society?”

Although Mr. Shayeb, who wrote the article charging corruption at the Palestinian mission in Paris, is said to be the first professional journalist to have been jailed by the Palestinian Authority for something he wrote, reports abound in the West Bank of others who have been questioned by the security services and threatened with prison.

The Facebook critics, for their part, either do not know the rules or have been trying to get around them.

Tareq Khamees, 24, a local journalist, said he was detained for questioning last month by Preventive Security officers, who also seized his laptop, for merely having posted a comment on Facebook in support of other detained journalists and bloggers. He said that he was released four hours later because about 50 colleagues marched in Ramallah to protest his detention.

Mr. Shayeb is out on bail but is being sued by the Palestinian foreign minister, as well as the ambassador to France and his deputy.

Mr. Shayeb has so far refused to reveal his sources to the authorities, but he said that eight lawyers had volunteered to defend him.

“When we go to court,” he said, “everyone will understand who is telling the truth and who is lying.”

Many, however, express little confidence in the legal system, describing it, at best, as chaotic.

“I believe 100 percent that we do not have an independent judicial system,” said Mr. Khraishi of the journalists’ syndicate. “You can quote me saying that, but no Palestinian media will publish it.”