The ruling follows a temporary injunction granted in May against the law, which goes beyond the perpetrators of the Sept. 11, 2001, attacks to people who are part of or “substantially” supported Al Qaeda, the Taliban or “associated forces” hostile to the United States or its allies. Chris Hedges, a journalist who formerly worked for this newspaper, and several supporters of WikiLeaks said it was too imprecise about the conduct that could lead to someone’s detention and exactly who could be detained.

The plaintiffs said the statute chilled their First Amendment rights because they feared the government might claim their activities made them supporters of an enemy force and subject to detention.

Judge Forrest agreed, saying the Constitution requires more specificity when “defining an individual’s core liberties.” She was especially troubled by the government’s inability to define terms like “substantially supported” and “associated forces,” despite ample opportunity to do so during the course of the lawsuit. She also was swayed by what she saw as the government’s failure to eliminate the plaintiffs’ fears by unequivocally stating that no First Amendment-protected activities would subject them to indefinite military detention.

The judge makes plain that the outcome would likely have been different had the government offered an authoritative official statement that “protected First Amendment activities occurring by Americans on American soil.” The failure to do so, she found, bolstered both the plaintiffs’ standing to sue, as well as their claims.

The judge’s willingness to take constitutional claims seriously was a refreshing departure from too many other judges in cases involving national security. If the government is unhappy with the ruling, it can largely blame its failure to adequately limit and define detention authority.