The groups and individuals who wanted to provide financial support and training for peaceful political purposes to the PKK and LTTE argued that the material support law violated their free speech rights and association rights, and that the law is unconstitutionally vague.
Justice Stephen Breyer lodged a dissent joined by Justices Ruth Bader Ginsburg and Sonia Sotomayor. Breyer read his dissent from the bench.
Breyer wrote, "The plaintiffs, all United States citizens or associations, now seek an injunction and declaration providing that, without violating the statute, they can (1) ‘train members of [the] PKK on how to use humanitarian and international law to peacefully resolve disputes'; (2) ‘engage in political advocacy on behalf of Kurds who live in Turkey'; (3) ‘teach PKK members how to petition various representative bodies such as the United Nations for relief'; and (4) ‘engage in political advocacy on behalf of Tamils who live in Sri Lanka.'"
"All these actions," Breyer continued, "are of a kind that the First Amendment ordinarily protects."
He continued, "In my view, the Government has not made the strong showing necessary to justify under the First Amendment the criminal prosecution of those who engage in these activities. All the activities involve the communication and advocacy of political ideas and lawful means of achieving political ends. Even the subjects the plaintiffs wish to teach - using international law to resolve disputes peacefully or petitioning the United Nations, for instance - concern political speech."
The opinion (pdf) is available here.
During the 2010 ACS National Convention, expert panelists examined the material support law and its constitutional implications. Video of that panel, "Material Support Provisions and the First Amendment," is available here.
The high court issued three other opinions today. For coverage of those opinions and other court action, see SCOTUSblog here.