Courts can sanction parties and counsel for filings made without a reasonable basis, for improper purposes, or for discovery abuse. The remedies range from a reprimand through fee-shifting to dismissal or default.
The certification standard. Signing a filing generally certifies that it is not presented for an improper purpose, that the legal contentions are warranted by existing law or a non-frivolous argument to change it, and that the factual contentions have evidentiary support or are likely to after investigation. The test is objective reasonableness at the time of filing, not hindsight.
Safe harbour. Many rules require the moving party to serve the motion and give the other side a period to withdraw the offending filing before it is filed with the court. Skipping that step is the most common reason sanctions motions fail on procedure rather than merits.
Discovery sanctions operate separately and are granted far more often — for failing to produce, failing to appear, or violating an order.
Practical judgement. Sanctions motions are expensive, rarely granted, and frequently damage the moving party’s credibility if they look like a tactic. The letter identifying the problem and inviting withdrawal usually achieves more than the motion, and it preserves the record if the conduct continues.