“Allowing the government to identify the emails and communications with the third parties, that appear to fall outside the government’s ‘focus[] group,’ endangers the First Amendment rights of anyone falling outside this ‘focus[] group,’ the brief said.

Aghaian pointed to a decision in the U.S. Court of Appeals for the D.C. Circuit last week, in which the court vacated a conviction because investigators used an overbroad warrant that allowed them to search a house and seize “all cell phones and electronic devices without regard to ownership” without probable cause. In DreamHost’s case, Aghaian wrote, the government is attempting to seize “all contents of email accounts that are within the @disruptj20.org domain” without probable cause.

The advocacy group Public Citizen has also asked to intervene in the case on behalf of individuals who visited the website. In a blog post Wednesday, Public Citizen lawyer Paul Levy wrote a “serious First Amendment issue” still remains with the warrant.

“Seizure of those emails would invade the right of the senders of those emails to speak anonymously, which is far better established in the law as a barrier to discovery than the right to read anonymously,” Levy wrote.