Human Rights Watch is urging the Iraqi government to cancel revocations of TV station licences.
Iraq's media commission suspended licences for 10 satellite television stations, halting their broadcasting.
The official Communications and Media Commission (CMC) suspended the licenses on April 28, 2013, amid spiralling violence and anti-government demonstrations in Sunni-majority provinces.
The license suspensions targeted exclusively opposition stations while leaving others like state-run al-Iraqiya channel free to continue broadcasting.
The suspended stations are: Al-Jazeera, Al-Sharqiya, Al-Sharqiya News, Al-Anwar al-Thany, Al-Fallujah, Al-Tagheer, Al-Garbhiya, Salah al-Din, Babeliya, and Baghdad TV.
"The authorities have admitted that there was no legal basis for their decision, which looks more suspicious given the government's history of cracking down on opposition media, particularly during protests," said Sarah Leah Whitson, Middle East director at HRW.
Mujahid Abu al-Hail, who heads the media commission's Department of Audiovisual Media Regulation, told HRW he took the decision to suspend the licences because the commission's "Monitoring Department" had concluded, after tracking the stations' output for three months, that their messaging encouraged violence and sectarianism.
He admitted that he did not make the decision "on a legal basis" but said it was on national security grounds because the stations had "broadcast speeches and fatwas from extremist sheikhs that encouraged violence".
He said the commission had documented examples of such incitement in a report that it would make available to HRW, although it has not yet done so.
HRW says the suspension was arbitrary.
Whitson said "blank screens will be a telling indication of what the Iraqi authorities see as acceptable journalism".
"The authorities have a responsibility to protect citizens, but also to protect their free speech and access to information."
Al-Hail told HRW that he had ordered the licence suspensions after the commission repeatedly warned the stations that their licenses would be suspended if they did not comply with broadcasting regulations and stop airing material deemed offensive.
Yet Ziyad al-Ajili, head of the Journalistic Freedom Observatory, which monitors media freedom in Iraq, said that the stations had told him they had received no prior notification. He said they first learned of their license suspensions in a statement on the CMC website.