A vote in the European Parliament’s civil liberties committee early next week will set the stage for a debate over Web content blocking and terror attacks. It comes during a jittery period of concern around extremist activity online following the atrocity in Orlando and the murder of British politician Jo Cox.

Back in March, national ministers set out a common position on the proposal for an EU law to combat terrorism. The original draft of the law from the European Commission focused on preventing terrorist attacks by criminalising preparatory acts, such as training and travel abroad for terrorist purposes, and made no mention of Web blocking. This was unsurprising, given that it was about criminalising particular offences and not specific obligations on companies.

However, ministers added a note in their version saying “it seems appropriate for member states to take measures to remove or to block access to webpages publicly inciting to commit terrorist offences.” Now, one MEP seems to have taken that idea and is running with it.

German politico Monika Hohlmeier has introduced two new sections to the proposed law that have other parliamentarians and digital rights' activists worried. The new text, taken in part from the EU law against child sex abuse, says that member states “may take all necessary measures to remove or to block access to webpages publicly inciting to commit terrorist offences."

Campaigners for digital rights say it's unclear how such allegedly “necessary” measures can be optional.

For them, a problem arises is in the phrase “this directive is without prejudice to voluntary action taken by the Internet industry to prevent the misuse of its services or to any support for such action by member states, such as detecting and flagging illegal content.” In plain English this means that safeguards proposed in the amendment that aim to defend proportionality and fundamental rights can be skipped if governments opt for voluntary schemes.

“This leaves the door wide open for private companies to police content and very likely over-block or delete any content they are unsure about,” EDRi (European Digital Rights) head Joe McNamee told Ars. He added that European law requires that any blocking or content restriction measures “must be provided for by law, subject to initial judicial control and periodic review.”

While Hohlmeier’s proposed amendments say that blocking is “necessary,” another MEP, shy of the limelight, told Ars that “no evidence has been put forward on this by anybody.” Earlier this month the Council of Europe also issued a warning that many European countries, including the UK, were in danger of going too far and over-blocking content.

The report criticised, in particular, content restrictions that do not have a clear legal framework. In 2015, the EU adopted legislation banning voluntary Internet blocking, a measure described as a “game-changer” by the Council of Europe document.

Estonian MEP Marju Lauristin told Ars she is very worried about the vote. She said she was disappointed about this so-called “compromise” and fully endorses the Council of Europe’s position/warning and plans to vote against it. Lauristin also believes that “this provision is jeopardising freedom of expression as enshrined in the Charter of Fundamental Rights of EU”. She added that she hopes the text will be improved in the coming days.

If the text is approved by the civil liberties committee, it will then be put to the parliament as a whole.