Goldsmith called Guantánamo a "symbol of injustice" and suggested that the prison camp was tarnishing the image of the United States and the West as a whole.
The Miami Herald's Carol Rosenberg reported on the ABA meeting.
Earlier, the ABA's House of Delegates adopted a resolution of support for the ''courageous lawyers'' who provide free-of-charge services to Guantánamo captives.
A senior Pentagon official in charge of detainee affairs, Charles ''Cully'' Stimson, himself a lawyer, lit a national legal firestorm by making a Jan. 11 broadcast call on corporate America to boycott firms whose lawyers represent Guantánamo captives.
Lawyers across the country protested that so-called pro-bono representation is a bedrock American principle. Stimson, who was deputy assistant secretary of defense for attorney affairs, apologized. Then he resigned.
The House of Delegates adopted the resolution by unanimous voice vote after impassioned addresses by three lawyers, among them New York Bar Association President Mark Alcott, who invoked the Pledge of Allegiance.
''It's not justice for some -- not justice for most,'' Alcott said. ``It's justice for all.''
The Pentagon has held men and teens from dozens of countries as ''enemy combatants'' at the remote U.S. Navy base for more than five years. Today they number about 395 -- none currently charged with a crime.
Tony Blair's government has successfully negotiated the release of all the British citizens held earlier at Guantánamo -- after, Goldsmith said, he offered the legal opinion that the United States could not guarantee them fair trials that met international legal standards.
Goldsmith said that British legal officials would ''provide more detail to the U.S. government'' of its concerns about the latest legislation.
He also took a swipe at Stimson's remarks.
''I assure you that remarks of that sort,'' he told the House of Delegates, ``are viewed from across the Atlantic as unjust, unacceptable and un-American.''