The IPA cited the 1998 Competition Act, which renders collective boycotting illegal. The law states that businesses must compete on a level footing and prohibits them from abusing a dominant position in the market.
The dispute that led to the proposed boycott of BBH centred on the agency's decision to pay editors directly, as opposed to via the production company.
However, the APA has defended itself by insisting there was never an actual ban on using the agency.
Steve Davies, the managing director of the APA, said: "There was not a boycott of BBH, simply each production company making its own mind up whether to accept, reject or negotiate BBH's terms. They want free negotiation of the terms appropriate to the job, rather than have the terms on which they could do business dictated to them on the PIBS (production and insurance briefing spec)."
Meanwhile, BBH has come to an agreement with production companies on jobs that are already running. It has removed the clause that states the agency will be contracting editors directly.
Frances Royle, BBH's head of TV, said: "In order to get live jobs through on schedule, we have negotiated a solution with the relevant production companies. However, the wider issue remains and must be dealt with."
Production companies including RSA Films, Blink, Academy, Stink, Gorgeous, Partizan and MJZ gathered at the APA last Tuesday to discuss the proposition of a ban on working with BBH.