Jeremy Corbyn's Brexit speech makes a lot of political sense, because now Labour can join with Soubry Tories and, if they wish, vote down May's withdrawal bills.
The speech, however, made no sense to anyone who knows anything about the EU. I was surprised to see it was so well-received. Even the usually sensible Martin Sandbu thinks the policy is "smart and realistic." (See the FT's editorial take here and the Guardian's here and Steve Peers here--although the Norths are unsurprisingly hostile--see here and here--as is Artie Shanker in Open Europe.)
Corbyn's new position certainly marks an improvement over earlier even less coherent positions. But that's not saying much, and the new position still has many problems.
Among these problems:--
1a. He seems to think that a Customs Union (which is basically a common external tariff) is sufficient to yield frictionless borders even in the case of "Just-in-Time" car manufacturing (his Mini example). You need to stay in the Single Market and maintain regulatory alignment to get that level of frictionlessness.
1b Ditto for Northern Ireland. A Customs Union would still require a border--especially so given the preponderance of agricultural products moving between NI and RoI.
2. He doesn't directly mention the ECJ--as if it can be wished away--but since he wants to maintain membership of European agencies, then he is accepting the oversight of this Court..
3. He fails to ask--"Why would this new Customs Union be in the EU's interests? Corbyn seems to think that the EU would allow the UK a say in future trade deals, which presumably would mean either (i) the UK gets a vote of equal weight to every other member state, or (ii) the UK gets a vote of equal weight to the other 27 member states combined.
Rather than have the UK inside the tent buggering-up future trade deals, the EU would surely prefer to keep the UK outside the tent suffering the consequences. If the production of Minis moves to Germany, Slovakia or elsewhere, all the better (see Faisal Islam's article on the car industry).
Indeed, if you parse this bit of Corbyn's speech, the difficulties become all the more apparent--
A. "The option of a new UK customs union with the EU would need to
ensure the UK has a say in future trade deals." [Legally impossible for the EU to ensure anything without a revision of its Treaties, Politically undesirable--why should the EU give the UK such "a say"?]
B. "A new customs arrangement would depend on Britain being able to negotiate agreement of new trade deals in our national interest." [why would the EU care about the UK's ability to strike new trade deals in its own national interest? are there any such new trade deals? See the recent intervention of Sir Martin Donnelly]
C. "Labour would not countenance a deal that left Britain as a passive recipient of rules decided elsewhere by others. That would mean ending up as mere rule takers. [If the UK doesn't want to be passive rule-takers, it should never have exited the EU.]
4. His opt-outs for public procurement etc are not only incompatible with EU rules but incompatible with WTO rules too.
5. You can't leave the EU without leaving Europe--just ask any American who wants to stay in Europe for more than 3 months in a year without a visa.
The more general difficulty with Corbyn's position is, like that of many British politicians and pundits, it fails to answer the question:
What self-interested reason does the EU have to accept your proposal?
In thinking about this question, it is important to remember two facts;
1. The EU is the more powerful party in this negotiation;
2. The EU's principal interests are (i) to maintain the coherence of the Single Market; and (ii) to ensure--whether through regulatory alignment or otherwise-- that a Level PLaying Field obtains between the EU and POst-Brexit UK.
