Short answer. Missing the brief is treated as missing the pre-trial itself. Rule 18, Section 6 requires each party to file and serve a pre-trial brief in a manner ensuring receipt at least three calendar days before the pre-trial, and states that failure to file it shall have the same effect as failure to appear.
What the law says
Failure to file the pre-trial brief shall have the same effect as failure to appear at the pre-trial.
Rule 18, Section 6 — Pre. Read the full provision →
The deadline is about receipt, not dispatch
The parties must file their briefs with the court and serve them on the adverse party in such manner as shall ensure their receipt thereof at least three calendar days before the date of the pre-trial. Note what the yardstick is: receipt, not mailing. A brief posted in time but received late does not comply. The obligation also runs in two directions at once — filing with the court and service on the other side — and both must land within the deadline. Counting is in calendar days, so weekends buy no extension.
What the brief must contain
The section prescribes the contents: A concise statement of the case and the reliefs prayed for, a summary of admitted facts and proposed stipulations, the main factual and legal issues to be tried or resolved, the propriety of referring factual issues to commissioners, the documents and object evidence to be marked with their purpose, the names of the witnesses, and the summary of their respective testimonies, and a brief statement of points of law with citation of authorities. The brief is, in effect, each side's trial plan disclosed in advance — which is why the Rules take its absence so seriously.
The sanction: treated as a no-show
The last sentence carries the teeth: Failure to file the pre-trial brief shall have the same effect as failure to appear at the pre-trial. Physically attending the hearing does not cure an unfiled brief; in the eyes of the Rules, a party without a brief was never there. Non-appearance at pre-trial is among the most dangerous defaults in civil litigation — for a plaintiff it puts the case itself at risk of dismissal, and for a defendant it risks the court letting the plaintiff present evidence without opposition. The brief, in other words, is not paperwork; it is attendance.
If the deadline is near or already missed
If the pre-trial date is approaching, get the brief filed and served by the fastest reliable means available — three calendar days of margin evaporates quickly. If the deadline has already passed, tell your lawyer immediately rather than hoping it goes unnoticed at the hearing: whether anything can still be done depends on the court and the circumstances, and any explanation is better made proactively than after the sanction lands. And treat the episode as a warning about the whole pre-trial stage, where positions, witnesses and evidence are locked in early.