The Law Society is considering legal action against DAS after the insurer issued a press release and promotional material that criticised the society's conditional fee insurance scheme.
DAS put out the release to promote the launch of Conditional Fee Insurance Services (CFIS), a new division set up to target the no win no fee insurance sector.
But the release says the Law Society's scheme called Accident Line has a number of "drawbacks".
A Law Society spokeswoman said: "We are certainly concerned about some of the things they [DAS] have said about us. They say things in their press release that we don't believe are true."
She would not confirm or deny whether legal action was likely. But a source close to the Law Society said: "They [the Law Society] are taking legal opinion. There were one or two remarks in the DAS press release which they believe could be factually incorrect."
DAS managing director Paul Asplin was in bullish mood. He hit back: "I must admit, I am not aware they have written to us, which should be the first course of action. But we would feel confident about what we say in the press release.
Under the Law Society scheme, which is arranged by Abbey Legal Protection, solicitors receive delegated authority to accept claims.
To access the service, solicitors must pay an annual fee.
The new CFIS scheme is free to enter and offers solicitors:
Asplin added: "We feel our product offers more, and we do believe their product has many drawbacks. Obviously we do feel confident, but if they do have a problem, we would be happy to talk to them."
The DAS boss said he hoped CFIS would bring down the cost of claims to the insurance industry by offering cheaper policies.