In 1952 Phillips was summoned to appear before the McCarran Commission, a judiciary subcommittee investigating internal security during the McCarthy era. Although Phillips appeared before a subcommittee hearing in New York and agreed to answer questions relating to her work as a scientist and physics educator, she invoked her Fifth Amendment rights when asked about other topics, including questions about whether she was a member of the Communist party. As a result of her refusal to cooperate with the commission as a matter of principle, Phillips, a highly regarded physics educator, was dismissed from her professorship at Brooklyn College and her part-time position at the Columbia University Radiation Laboratory. She remained unemployed as a college professor for five years.