The Bar Council's decision to allow more contact for witnesses has been challenged by the Lord Chancellor's Advisory Committee on Legal Education and Conduct (Aclec).
In a letter to the Bar Council Aclec says it has "considerable reservations" about the proposed amendments to the current rules.
It adds that the committee "has expressed considerable concern at the Bar's purported general waiver of the current rule. The committee does not believe it can be an appropriate use of the waiver power in effect to anticipate or pre-empt the procedure for amendment of its rules of conduct."
It continues: "The committee would like the waiver to be rescinded without delay."
The issue was expected to take priority at last weekend's Bar Council meeting, originally arranged to debate the proposed shake-up of the Bar's complaints system.
The witness proposal was made in the Bar Standards Review Body report last September, based on proposals stemming from Lord Runciman's Royal Commission on Criminal Justice.
A Bar source said: "We would not make any secret of the fact that Aclec's Pirandelloesque search for a role does get up peoples' noses. That's what happened here."
A Bar Council spokesman said: "The Bar Council and criminal practitioners have worked hard on this. We are not amused that their organisation [Aclec] is now having reservations. The timescale for Aclec considering this has been at least 12 months."
There is speculation that this latest example of Aclec falling out with the legal profession will encourage further calls for its disbandment.
An Aclec spokesman said: "This is currently a private discussion with the Bar Council. We have no comment at all."
The committee wishes to discuss the matter with the Bar as soon as possible.