The ACLU's lawsuit had to be kept secret by law?

The ACLU had to keep secret its lawsuit in protest of a particular law, because if it didn't keep the lawsuit secret it would be violating said law. Wow. I am living in some weird, weird times.
Reuters: Judge Rules Against Patriot Act Provision:
Marrero, stating that "democracy abhors undue secrecy," found that the law violates constitutional prohibitions against unreasonable searches. He said it also violated free speech rights by barring those who received FBI demands from disclosing they had to turn over records.

Because of this gag order, the ACLU initially had to file its suit against the Department of Justice under seal to avoid penalties for violation of the surveillance laws.