The resolution passed on a voice vote Tuesday in San Francisco, the ABA Journal reported. A long list of speakers supported it with only one calling on the House to reject it.
Leslie W. Jacobs, past president of the Ohio State Bar Association and partner in a Cleveland firm, suggested the resolution would reduce the ABA's influence with legislators.
"If we are perceived to be off-base on something that lawmakers readily understand, I don't think they can be expected to defer to us on something on which they don't understand," Jacobs said.
Last year, the ABA called for the repeal of the section of the U.S. Defense of Marriage Act that bars legally married same-sex couples from receiving the same federal benefits as other spouses.
Last week, a federal judge overturned Proposition 8, an amendment to the California Constitution that annulled a state Supreme Court ruling allowing gay marriage.