Theresa May's two-year Brexit timeframe is 'totally impossible'
Jean-Claude Piris, the head of the EU Council's legal service from 1988 to 2010, told the Financial Times that the complexity of striking a trade deal means the process "could take up to ten years," and only less if there was "goodwill on both sides."
May told MPs on December 20 that she expects to negotiate a formal deal with the EU by the time Britain completes its scheduled exit from the union in two years' time.
Piris, who drafted several major EU treaties including Lisbon and Maastricht, said that a trade deal would involve "thousands of pages and hundreds of articles," and called on the UK to arrange a transition deal to avoid "a catastrophe."
May hinted earlier in December that she may favour a transitional deal, but was characteristically vague on detail. She said: "I would expect us to be able to negotiate a deal within the two-year period that is set out, but it may be the case that there are some practical aspects which require a period of implementation thereafter."
"We will discuss whether we need an implementation phase," she added.
"You vitally need a transition period," Piris told the Financial Times. He warned that the UK otherwise risks falling into the "WTO gap," whereby it operated under costly World Trade Organisation tariffs until it made other free-trade arrangements.
Piris outlined two potential models for a transitional deal. The first would involve Britain staying in the single market for a few years after Brexit, but that would involve keeping free movement obligations - something May intends to avoid.
The second option would see Britain leave the single market but remain in the customs union, similar to Turkey, which Piris described as a "much more modest" proposal, as it would allow Britain to place curbs on immigration at the same time as avoiding the "WTO gap."