The contrasting fortunes of three Arab Twitter users

Traditional media in Arab Gulf states predominantly consists of government-controlled broadcasters and newspapers with government-appointed editors. This, allied with social conventions that emphasise respect for authority and one's elders, does not provide a climate which allows energetic questioning of personalities or official policies.

The region is experiencing rapid growth of social media, generating lively debate online. So far the authorities, rather than resorting to large-scale blocking of sites, seem to have adopted a policy of monitoring, and taking action against individual users or posts that create a stir. The result is raising questions about what is and is not socially and legally acceptable comment in the region.

Three users of Twitter that I look at here have experienced very different consequences after posting controversial comments. In part, different treatments can be attributed to the differing social positions of the authors and different political circumstances. One tweet considered insulting to a whole community has landed its sender in jail, while others that are equally insulting go unpunished.

In June, Nabeel Rajab, head of the Bahrain Centre for Human Rights, was arrested and subsequently sentenced to three months imprisonment for comments he posted on Twitter that were deemed to be defamatory. Rajab is a prolific Twitter user with more than 170,000 followers and a high international profile.

He had called for the resignation of the country's long-serving prime minister and said that the residents of a Sunni-majority district had only welcomed the premier during a visit because he had offered them subsidies.

On 23 August an appeals court overturned the conviction. But Rajab remains in jail, where he is serving a sentence of three years on charges of organising and participating in illegal protests.

Another Twitter user, who seems oblivious to concerns about defamation, is the police chief of Dubai: Lt-Gen Dahi Khalfan. In June, he sent out a series of tweets saying that the election of the Muslim Brotherhood's Muhammad Mursi as president of Egypt would be "a disaster" for the region. He has since called Mursi "a thief" and labelled the Brotherhood dangerous thugs.

More recently, he caused outrage in Kuwait when he tweeted against opposition plans to hold a rally to protest over election laws. Khalfan said that the protesters were "a bunch of fools".

When this comment drew criticism, he responded by saying that Kuwait is a country where "prostitution is prevalent".

A third Twitter user, Muhammad Al al-Shaykh, a columnist for the Saudi daily Al-Jazirah, recently sparked a furore over a remark he posted on Twitter about Saudi women practising prostitution in Dubai. Al-Shaykh said his comment needed to be understood in context, as it had been made during a discussion about poverty and female unemployment in Saudi Arabia.

But many critics reacted as if had slandered the whole female population of Saudi, and there were calls for legal action to be taken against him. One Saudi cleric said he should receive "severe punishment".

In previous cases there have been calls for the execution of people posting tweets that were thought to be blasphemous, while a Kuwaiti user was sentenced to seven years in prison for sectarian comments.

These cases highlight the extreme sensitivity of a number of topics such as religion and national pride and identity. But they also show how the boundaries between private and public discourse have blurred.

New media are challenging the existing social conventions and offering the opportunity to express views much more outspokenly than in the restricted formats that apply in traditional mainstream media.

What has yet to be determined is what limits, whether judicial or consensual, are put on this new medium of expression.