Forty-three years ago, when the nation lived in fear of Communist sympathizers and saboteurs, the Supreme Court said that even the need for national defense could not reduce the First Amendment rights of those associating with American Communists.

On Monday, in the first case since the Sept. 11, 2001, attacks to test free speech against the demands of national security in the age of terrorism, the ideals of an earlier time were eroded and free speech lost. By preserving an extremely vague prohibition on aiding and associating with terrorist groups, the court reduced the First Amendment rights of American citizens.

The case was not about sending money to terrorist organizations or serving as their liaison, activities that are clearly and properly illegal. And it did not stop people from simply saying they support the goals of groups like Hamas or Al Qaeda, as long as they are not actually working with those groups. But it could have a serious impact on lawyers, journalists or academics who represent or study terrorist groups.

The case arose after an American human rights group, the Humanitarian Law Project, challenged the law prohibiting “material support” to terror groups, which was defined in the 2001 Patriot Act to include “expert advice or assistance.” The law project wanted to provide advice to two terrorist groups on how to peacefully resolve their disputes and work with the United Nations. The two groups  the Liberation Tigers of Tamil Eelam and the Kurdistan Workers’ Party  have violent histories and their presence on the State Department’s official list of terrorist groups is not in dispute.