Berkowitz joined the Bank of England five years ago from Linklaters & Paines. But he has decided to join rival magic circle giant Freshfields when his term at the bank comes to an end in January.
He will join as a senior consultant on a three-day per week basis. His remit will mainly include advising on strategic direction. But he will also be involved in bedding down the firm's recent merger with Bruckhaus Westrick Heller Löber, particularly addressing any client conflicts.
Berkowitz will also work alongside partner in charge of training Hugh Crisp and may also do some teaching, says Freshfields' senior partner Anthony Salz.
Berkowitz took over from Peter Peddie at the Bank of England in 1996. Peddie, a former Freshfields partner, became the first adviser to the governors and head of the legal unit when he joined the bank in 1992.
Berkowitz's main responsibilities at the bank included advising the governors and the board of banking supervision on a host of legal issues.
Salz and Berkowitz have known each other for several years, most notably through Freshfields' work for the Bank of England.
Berkowitz says: "It is a part time senior consultant position advising on some of the policy strategy. I have worked with [Freshfields] a great deal over the years and they asked me to come on board."
Berkowitz had been with Linklaters since 1967 before joining the Bank of England. But he says that the prospect of returning to Linklaters in a similar role to the Freshfields' position was not something that appealed to him because he "wanted to do something different".
Salz confirms there will be no changes to the central management team of himself, chief executive Alan Peck and managing partner Ian Terry. "He is going to sit close to Alan, myself and Ian. It will be helpful to have someone else because we are quite a bit bigger," says Salz.
It is hoped that Berkowitz will join the firm in March after leaving the Bank in January. The Bank of England was unavailable for comment, but it is understood that it has yet to finalise Berkowitz's replacement.