The system by which most chambers select their pupils is facing collapse following a row between the two premier public law sets.
The Lawyer understands a letter written by Michael Beloff QC, head of chambers at 4-5 Gray's Inn Square, accuses Blackstone Chambers of poaching all the best bar students.
The problem is the Pupillage Application Clearing House (PACH). This system, which processes student applications for bar pupillages, gives sets operating outside of the scheme first choice of plum pupils.
Chambers signed up to PACH can only begin recruiting in September. Sets outside of the system - including Blackstone and leading commercial sets 7 King's Bench Walk, John Powell QC's 2 Crown Office Row, Serle Court, 4 Paper Buildings, 4 Pump Court and 3-4 South Square - have often already made their selections.
Beloff, a co-founder of the PACH scheme, has written to Bar Council chairman Dan Brennan QC complaining that his chambers is missing out on the best students.
Blackstone was originally a member of PACH but pulled out two years ago because it felt the system was unfair to students. Chief executive at 4-5 Gray's Inn Tony Wells stresses that the dispute is not with Blackstone but with the regulations themselves.
A source at one of the magic circle sets voiced a sentiment echoed in many other commercial chambers, saying: "We are seriously unhappy with the PACH system and we are considering our position."
The Bar Council is desperately trying to make changes to the scheme, before it all falls apart.
Nigel Bastin, head of education and training at the Bar Council, says the changes, if given the go-ahead, will prevent chambers, even non-PACH members, offering a place to students before 1 September in their final year of university. This reflects a similar practice adopted by the Law Society.
There would also be a closed period between 1 May and 1 September in the final year of university when no offers can be made.
No set, regardless of membership to PACH, will be able to require a student to accept a pupillage offer before PACH's acceptance deadline.
But the consultation is not likely to receive a positive response from sets outside of PACH, or those currently considering their position'. One set is understood to be considering a judicial review of the bar's proposed changes should they come into force.