The Federal Election Commission demonstrated a rare burst of productivity Thursday, when commissioners settled one major issue, investigated another, but put off a brewing fight over how it conducts investigations for another day. 

The Republican and Democratic commissioners had no trouble giving the green light to requests brought by two separate committees to treat same-sex married donors the same as opposite-sex donors. Married donors can jointly contribute $10,400 to a candidate, even if only spouse earns income. The move was expected after the Supreme Court's reversal of the Defense of Marriage Act. 

The  commissioners were also unified in ...