Why King & Spalding backed out of the DOMA case.

TPM reports:

Sources with knowledge of the backlash confirm that one of King & Spalding's top clients, Coca Cola, also based in Atlanta, directly intervened to press the firm to extricate itself from the case....

Other King & Spalding clients likewise conveyed to the firm that its decision to take the DOMA case could cause them problems, both internally and with customers...

King & Spalding also faced escalating protests from gay rights groups. The LGBT community in Atlanta has significant political influence, and the firm quickly became a target for major gay rights organizations including the Human Rights Campaign and the group Georgia Equality -- the largest gay rights advocate in the state. The groups planned an aggressive ad campaign, direct communication with the firm's clients, and a diminution of its Corporate Equality Index ranking -- the metric HRC uses to track corporate support for gay rights....

Complicating matters for King & Spalding, the firm's contract with the House of Representatives contained a curious provision that seemingly barred firm employees -- even those not involved with the case -- from advocating for gay equality in their private capacities outside the firm, so long as the firm was defending DOMA. Employees, the contract stated, "will not engage in lobbying or advocacy for or against any legislation [to] alter or amend in any way the Defense of Marriage Act."

According to the National Law Journal, "Gay-rights lawyers interpret that to be a gag order for firm employees." That includes one employee, Atlanta associate Brian Basinger, who is president of the Stonewall Bar Association of Georgia, a group that pushes for gay rights.