Socialist leaders in the European Parliament have threatened to sabotage and “never agree” to David Cameron’s much touted “deal” to curb migrant benefits, just as legal experts warn the deal is not “legally binding” despite the Prime Minister’s assurances.

Italian MEP Gianni Pittella speaks for the second largest group in the European Union (EU) assembly. This Wednesday, he labeled Mr. Cameron’s “emergency brake” on migrant benefits “discrimination”.

Professor Steve Peers, who has worked as consultant for the European Parliament and the European Commission, as well as the House of Lords Select Committee on the European Union, agreed. He said that the policy was likely to be challenged in courts as “discrimination”.

Like others before him, Mr. Pittella pointed out that the welfare element of the deal will need to be translated into new legal proposals by the European Commission, and that MEPs will have the right to table amendments.

“The European Commission will need to put provisions through parliament. At that point we will be able to examine and debate them,” Mr. Pittella said during a debate, EUobserver reports.

“I will never agree that eastern European workers are seen as second-class citizens”, added Rebecca Harms, a leading German MEP in the Green group.

“Imagine two young people – Europeans, same job, same work – there is a danger one would have fewer rights than the other” said Mr. Pittella, explaining the socialist perspective, “we don’t want to see any distinction between rights in the European Union.”

Last week Michael Gove, a Brexit supporting minister and the Secretary of State for Justice, also pointed out that the deal was not legally-binding and could be overturned by European courts.

The Prime Minister’s office quickly scrambled the Attorney General Jeremy Wright to deny the claims. President of the European Council Donald Tusk, keen not to lose the second biggest financial contributor to the EU, also stood up to say Mr. Gove was wrong.

A leading expert on European law, Essex University’s Professor of EU Law Steve Peers, has now sided with Mr. Gove in the dispute.

Professor Peers, who writes extensively on the subject and edits the EU Law Analysis website, has said that while parts of the deal are legally binding, others depend on later implementation and can be reversed – including the benefit “emergency brake”.

He told EurActiv that the “brake” was likely to face legal challenges in both domestic and EU courts on the grounds it broke EU law on discrimination between citizens.

“It would have to apply to a particular case,” said Professor Peers. “When this person, say a Polish plumber, is denied in-work benefits, he could take that to a British court.”

“The EU court would decide on that, and there is some chance the emergency brake would not go ahead if the EU Court struck it down. There is that possibility,” he said.

He stressed, a European court “has the final say on the deal, if someone comes along and challenges it under EU law. It will ultimately be the EU court that decides that…”

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