Story highlights Two partners at the intelligence firm declined to answer questions

They appeared before the House intelligence committee

Washington (CNN) Two partners at the intelligence firm that produced the dossier of memos alleging Russian efforts to aid Donald Trump's presidential campaign on Wednesday declined to answer questions before the House intelligence committee.

Fusion GPS' Peter Fritsch and Thomas Catán invoked their Fifth Amendment rights not to answer questions during their closed-door appearance before the committee, according to their attorney Joshua Levy.

After the session, which lasted more than an hour, Levy charged that the committee broke with its past practices by requiring them to physically appear to plead the Fifth.

"No American should have to experience the indignity that occurred today," Levy told reporters. "No American should be required to appear before a congressional committee just to invoke his constitutional privileges. But that is what Chairman (Devin) Nunes required of our clients at Fusion GPS today, in a sharp departure from even the past practice of this committee's investigation, where witnesses under the exact same circumstances were excused from appearing."

On Monday, Fusion GPS responded to the committee's subpoena by accusing Nunes -- the California Republican who has stepped aside from the committee's Russia probe -- of a "clear abuse of power," arguing that the subpoena violated the partners' First Amendment rights.

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