The case is United States v. Yassin, in which Safya Roe Yassin is being prosecuted for allegedly tweeting threats against U.S. military members and FBI agents. One can argue whether the tweets are properly seen as indeed true threats of violence or instead as solicitation of violence against particular targets (and if they are solicitation and not true threats, then she would need to be re-indicted for violation of the solicitation statute rather than the true threats statute). But one way or the other, the tweets seem likely to be constitutionally unprotected speech.
The particular Justice Department argument that people have noticed, though, doesn’t have to do with Yassin’s guilt as such, but rather with whether she should be detained before trial, which is what a magistrate judge ordered. The government is arguing that the magistrate judge’s order should stand, because “no condition or combination of conditions will reasonably assure the appearance of the person as required and the safety of any other person and the community” (the statutory standard for pretrial detention); here is the part that mentions the retweet:
Her virulent diatribe continued with an August 19, 2015, Twitter posting of the names of 150 United States Air Force personnel that listed these service members’ towns of residence and phone numbers. That same link encouraged her Twitter followers to “… Rejoice, O supporters of the Caliphate State, with the dissemination of the information to be delivered to lone wolves. God said: And slay them wherever you may come upon them.” Her unrelenting support of ISIS/ISIL was patently obvious in her verbatim retweets on August 24, 2015, that alerted her followers of two FBI employees who were “wanted to kill” and listed these employees actual names, city, state, zip code, and phone numbers.
Whether or not retweets are generally endorsements, the original tweet here sounds as though it solicited the murder of named people; and retweeting such a solicitation — coupled with the rest of Yassin’s alleged actions — seems like pretty strong evidence that she is endorsing the solicitation. The government might or might not be able to prove Yassin’s guilt beyond a reasonable doubt at trial; but the government’s use of the retweet as to the pretrial detention question seems quite reasonable.