Many prominent reformers have been arrested on the orders of the judiciary in recent months, but this was the first time a serving deputy had been detained for comments made on the floor of parliament.
A reformist member of the Iranian parliament has been released on bail after being arrested on the orders of a civil service court in Tehran.
Fatima Haqiqatjou had been detained on charges of inciting public opinion and insulting the judiciary.
Her detention on Tuesday provoked a storm of protest from parliament, which has been dominated by her fellow reformists since last year's general election.
Many prominent reformers have been arrested on the orders of the judiciary in recent months, but this was the first time a serving deputy had been detained for comments made on the floor of parliament.
Mrs Haqiqatjou was taken away from her home after being arrested by court agents.
She was later released on bail, the implication being that the case against her will continue.
'Judicial harassment'
A summons had been issued by the court earlier in the month and sent to the chamber's presiding board, but it declined to pass it on to her on the grounds that the move was in breach of the constitution and of parliamentary statutes.
A large majority of the deputies signed a motion calling for an emergency debate on what they called, the unconstitutional action by the court. They also called for and end to the judicial harassment of MPs.
The arrest was also condemned by the biggest of the reformist parties, the Participation Front - it said the judiciary was fomenting political tensions.
Newspaper closures
The case brings to a head a dispute between parliament and the hard line judiciary that has intensified in recent weeks as the arrest of reformists and the closure of liberal newspapers has gathered pace.
Many deputies have accused the judiciary of pursuing a one-sided legal vendetta against reformists with the aid of undermining the reform movement and its main figure-head, President Mohammad Khatami.
He has yet to announce whether he will stand for re-election in the June polls.
His supporters believe the judiciary's campaign is intended either to dissuade him from running or to make him appear weak and ineffective and thus discredit him in the eyes of the 20m people who voted for him last time, in the hope of bringing about change.