NEW YORK — The list of those caught up in the global surveillance net cast by the National Security Agency and its overseas partners, from social media users to foreign heads of state, now includes another entry: US lawyers.
A top-secret document, obtained by former NSA contractor Edward J. Snowden, shows that a US law firm was monitored while representing a foreign government in trade disputes with the United States.
The disclosure offers a rare glimpse of a specific instance of Americans ensnared by the eavesdroppers and is of particular interest because US lawyers with clients overseas have expressed growing concern that their confidential communications could be compromised by such surveillance.
The government of Indonesia had retained the law firm for help in trade talks, according to the February 2013 document. It reports that the NSA’s Australian counterpart, the Australian Signals Directorate, notified the agency that it was conducting surveillance of the talks, including communications between Indonesian officials and the US law firm, and offered to share information.
The Australians told officials at an NSA liaison office in Canberra, that “information covered by attorney-client privilege may be included” in the intelligence gathering, according to the document, a monthly bulletin from the Canberra office.
The law firm was not identified, but Mayer Brown, a Chicago-based firm with a global practice, was then advising the Indonesian government on trade issues.
On behalf of the Australians, the liaison officials asked the NSA general counsel’s office for guidance about the spying. The bulletin notes only that the counsel’s office “provided clear guidance” and that the Australian eavesdropping agency “has been able to continue to cover the talks, providing highly useful intelligence for interested US customers.”
The NSA declined to answer questions about the reported surveillance, including whether information involving the US law firm was shared with US trade officials or negotiators.
Duane Layton, a Mayer Brown lawyer involved in the trade talks, said he did not have any evidence that he or his firm had been under scrutiny by Australian or US spy agencies.
“I always wonder if someone is listening, because you would have to be an idiot not to wonder in this day and age,” he said in an interview. “But I’ve never really thought I was being spied on.”
Most attorney-client conversations do not get special protections under US law from NSA eavesdropping. Amid growing concern about surveillance and hacking, the American Bar Association in 2012 revised its ethics rules to explicitly require lawyers to “make reasonable efforts” to protect confidential information from unauthorized disclosure to outsiders.
Last year, the US Supreme Court, in a 5-to-4 decision, rebuffed a legal challenge to a 2008 law allowing warrantless wiretapping that was brought in part by lawyers with foreign clients they believed were probable targets of NSA monitoring.
The attorneys contended that the law raised risks that required them to take costly measures, such as traveling overseas to meet clients, to protect sensitive communications. But the Supreme Court dismissed their fears as “speculative.”
The NSA is banned from targeting Americans, including businesses, law firms, and other organizations based in the United States, for surveillance without warrants, and intelligence officials have repeatedly said the NSA does not use spy services of its partners in the so-called Five Eyes alliance — Australia, Britain, Canada, and New Zealand — to skirt the law.
Still, the NSA can intercept the communications of Americans if they are in contact with a foreign intelligence target abroad, such as Indonesian officials. The NSA then is required to follow so-called minimization rules to protect their privacy, such as deleting the identity of Americans or information that is not deemed necessary to understand or assess the foreign intelligence before sharing it with other agencies.
An NSA spokeswoman said the agency’s Office of the General Counsel was consulted when issues of potential attorney-client privilege arose and could recommend steps to protect such information.
“Such steps could include requesting that collection or reporting by a foreign partner be limited, that intelligence reports be written so as to limit the inclusion of privileged material and to exclude US identities, and that dissemination of such reports be limited and subject to appropriate warnings or restrictions on their use,” said Vanee M. Vines, the spokeswoman.
The Australian government declined to comment about the surveillance. In a statement, the Australian Defense Force public affairs office said that in gathering information to support Australia’s national interests, its intelligence agencies adhered strictly to their legal obligations, including when they engaged with international counterparts.
Several newly disclosed documents provide details of cooperation between the United States and Australia, which share facilities and sensitive intelligence, including efforts to break encryption and collect phone data in Indonesia. Both nations have trade and security interests in Indonesia, where Islamic terrorist groups that threaten the West have bases.
The NSA bulletin did not identify which case was being monitored by Australian intelligence, but Indonesia has been embroiled in several disputes with the United States in recent years. One involves clove cigarettes, an Indonesian export.
Andrew M. Perlman, a Suffolk University law professor who specializes in legal ethics and technology issues, said the growth of surveillance was troubling for lawyers. He helped create the bar association’s ethics code revisions that require lawyers to try to avoid being overheard by eavesdroppers.