In light of Talking Point Memo's claim that Coca-Cola directly intervened to have King & Spalding drop its defense of DOMA, legal scholar Richard Painter suggests that Coca-Cola may be required to answer some pointed questions:

Absent a client confict, one client should not be permitted to dictate the representation -- or the discontinuance of representation -- of another client.

The House can now demand an answer -- did Coke call K&S about the DOMA litigation and what did they say?

K&S will have to answer.

First, if this communication was made it occurred during the prior representation and concerns the subject matter of the prior representation, so K&S has a duty to disclose it to the client. See ABA Model Rule 1.4.

Second, this is not a privileged communication by Coke because it was not made for the purpose of seeking legal advice -- or assessing any possible conflict with K&S's representation of Coke. If was made to interfere with the representation of another client.

If K&S does not answer questions from the House about this, the House might consider a subpoena.

Hat/tip: Volokh Conspiracy blog