On Wednesday, Judge Dow ordered Badway to tell clients, who were not in court, that they must appear before her Sept. 14 after giving sworn depositions on what happened to the money at Badway's law office on Monday morning. Dow also voiced concern that McClure and D'Amico will attempt to flee her jurisdiction.
The phrase can be seemingly parsed into two different ways:
[they must appear before her(in front of her)] {(on) Sept. 14}: in this case, the prep 'on' is omitted
[they must appear] {before her Sept. 14}: I'm not sure if the phrase "her Sept. 14" could really make sense. If it does, it sounds like Sept. 14 is a timeline in her schedule list.
So, what would be the correct way to understand it? I feel the first one looks more correct or plausible.
The full source.