To write an opposition brief, you respond to the other side’s motion with a document that states the correct legal standard, lays out your version of the facts with citations to the record, argues point by point why the motion should be denied, and gets filed on time in the format your court requires. The federal rules set the floor, and your district’s local rules fill in the specifics on page limits, deadlines, and formatting. Miss the deadline or skip the response, and the court can rule on the motion with only your opponent’s version in front of it.
When an Opposition Is Required
Any substantive motion the other side files deserves a written response. The ones that most urgently demand a full opposition are dispositive motions, which can end part or all of the case without a trial.
A motion to dismiss under Federal Rule of Civil Procedure 12(b)(6) argues that even accepting every fact in your complaint as true, the law doesn’t give you a viable claim.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections Your opposition needs to show the complaint states a plausible legal claim and the case should proceed to discovery. A motion for summary judgment argues the undisputed facts entitle the moving party to win as a matter of law.2Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment Opposing summary judgment carries a heavier burden because you must point to specific evidence showing a genuine factual dispute that only a trial can resolve.
Non-dispositive motions matter too. Motions to compel discovery, motions to exclude evidence, and requests for temporary restraining orders all warrant a written response. Skip the opposition and the court rules without your input.
Calculating Your Deadline
The clock starts from the date the motion is served, and the length depends on the type of motion and your court’s local rules. Federal district courts set opposition deadlines somewhere in the range of 7 to 21 days. A common framework is 14 days for most motions and 21 days for summary judgment, but your court’s rules may differ.
Federal Rule of Civil Procedure 6(a) tells you how to count. Exclude the day the motion was served, count every calendar day including weekends and holidays, and include the last day. If the deadline falls on a Saturday, Sunday, or federal holiday, it extends to the next business day.3Legal Information Institute. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time For electronic filing, the deadline expires at midnight in the court’s time zone.
One rule catches people off guard. If you were served by mail, by leaving papers with the clerk, or by another non-electronic method the parties agreed to, you get an extra 3 days.3Legal Information Institute. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time The extension does not apply when service happens electronically through the court’s filing system. Calendar the date the day you receive the motion.
Structure of the Brief
Every opposition brief starts with the court caption, the case name, and the case number. The document title below the caption should identify what it is and which motion it answers, for example “Plaintiff’s Brief in Opposition to Defendant’s Motion for Summary Judgment.”
The body follows a predictable sequence:
- Introduction: a short overview of why the motion should be denied.
- Statement of facts: your version of the relevant facts, supported by citations to the record.
- Legal argument: the core of the brief, organized into clearly labeled sections addressing each ground for denial.
- Conclusion: a concise statement of the relief you want, usually denial of the motion in full.
- Signature block: attorney name, bar number, address, and contact information.
- Certificate of service: a statement confirming how and when the brief was delivered to the opposing party, when one is required.
Formatting and Page Limits
Physical formatting varies by court, but some standards are nearly universal: 8.5-by-11-inch paper, at least one-inch margins, double-spaced body text, and a readable font in 12-point or 14-point size. For appellate briefs, Federal Rule of Appellate Procedure 32 codifies these requirements and specifies that proportionally spaced type must be at least 14 points.4Legal Information Institute. Federal Rules of Appellate Procedure Rule 32 – Form of Briefs, Appendices, and Other Papers Trial courts set their own formatting through local rules, and font, spacing, and page specifics can differ between courthouses.
Page limits are where local rules bite hardest. Many federal districts cap opposition briefs at 15 pages for non-dispositive motions and 25 to 30 pages for dispositive motions like summary judgment. Some courts use word-count limits instead. Longer briefs often require a table of contents and a table of authorities listing every case, statute, and rule cited. Check the local rules before drafting, not after.
Redaction
Federal Rule of Civil Procedure 5.2 requires you to redact certain personal information from any document filed with the court. If your brief or its exhibits contain Social Security numbers, taxpayer identification numbers, birth dates, names of minors, or financial account numbers, you must truncate them. Include only the last four digits of Social Security and financial account numbers, only the birth year, and only a minor’s initials.5Legal Information Institute. Federal Rules of Civil Procedure Rule 5.2 – Privacy Protection for Filings Made with the Court The clerk’s office will not catch redaction failures. Filing unredacted information waives the protection for that data.
Building the Factual Record
The facts section is where many cases are won or lost, especially on summary judgment. Every factual assertion must cite specific evidence already in the record. Rule 56(c) lists what counts: depositions, documents, electronically stored information, affidavits or declarations, stipulations, admissions, and interrogatory answers.2Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment Unsupported factual claims are worse than useless, because the court can treat any fact you fail to properly address as undisputed.
Many courts require the party opposing summary judgment to respond to the movant’s statement of undisputed material facts point by point. For each listed fact, you either admit it, deny it with a citation to contradicting evidence, or explain why the cited evidence doesn’t actually support the claim. Skipping items or responding with vague denials is a fast way to lose. If the court treats a fact as undisputed because you didn’t properly contest it, that fact can support granting summary judgment.2Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment
Declarations in Place of Affidavits
When you need a witness’s sworn statement, you don’t necessarily need a notary. Under 28 U.S.C. ยง 1746, a written declaration signed under penalty of perjury carries the same weight as a notarized affidavit.6Office of the Law Revision Counsel. 28 US Code 1746 – Unsworn Declarations Under Penalty of Perjury The declaration must rest on personal knowledge, set out facts that would be admissible at trial, and show the signer is competent to testify to them. For declarations signed within the United States, the required closing language is: “I declare under penalty of perjury that the foregoing is true and correct. Executed on [date].” The same evidentiary standards apply to declarations and affidavits, so a declaration is not a shortcut for weak evidence.
If You Need Discovery to Oppose
Sometimes the other side moves for summary judgment before you’ve had a chance to complete discovery on the very facts the motion turns on. Rule 56(d) addresses this. If you can show by affidavit or declaration that you cannot yet present the facts needed to oppose, the court can defer ruling, deny the motion outright, or give you additional time to take discovery.2Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment The affidavit must be specific about what facts you expect to find and why you haven’t obtained them yet. A vague assertion that you need more discovery won’t work.
Writing the Legal Argument
The legal argument is the heart of the brief. Your job is to convince the judge that the moving party applied the wrong legal standard, misread the authorities, or ignored facts that change the outcome.
Start by stating the precise legal standard the court will apply. For a motion to dismiss, the question is whether the complaint states a plausible claim for relief with all factual allegations read in your favor. For summary judgment, the question is whether any genuine dispute of material fact exists that requires a trial.2Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment The non-moving party must go beyond the pleadings and point to specific facts in the record showing a trial is necessary. Framing the standard early anchors the judge’s analysis in your favor.
Organize the argument into clearly labeled sections, each addressing a distinct reason the motion should fail. In each section, state the legal rule, apply it to your facts, and explain why the movant’s contrary argument doesn’t hold up. When the other side cites case law, distinguish it. Show how the facts or legal context differ from your situation. A case involving an arm’s-length commercial transaction may carry little weight in a dispute between an employer and employee even when the same statute applies.
Where the movant relies on a statute, demonstrate that the text, purpose, or legislative history supports your reading. Cite controlling authority from your jurisdiction first, then persuasive authority from other courts if no binding precedent exists on point. Judges notice when a brief leads with out-of-circuit cases and buries unfavorable precedent from their own circuit. If binding authority cuts against you, address it directly and explain why it doesn’t control the facts of your case.
Filing and Service
Nearly all federal courts require electronic filing through CM/ECF. Convert the brief to a text-searchable PDF before uploading through the court’s portal. Many courts require the file to be flattened so it contains no fillable form fields. Electronic signatures in the format “/s/ [Attorney Name]” are standard for electronically filed documents.7Legal Information Institute. Federal Rules of Civil Procedure Rule 5 – Serving and Filing Pleadings and Other Papers
Service on the opposing party happens automatically when you file through CM/ECF, because the system notifies all registered users in the case. When electronic service occurs this way, you do not need a separate certificate of service.7Legal Information Institute. Federal Rules of Civil Procedure Rule 5 – Serving and Filing Pleadings and Other Papers If a party is not a registered electronic filer, such as a pro se litigant who hasn’t signed up, you must serve them by mail or hand delivery and file a certificate of service stating how and when delivery was made.
Check the filing confirmation the system generates. A brief that appears submitted on your screen but didn’t go through because of a formatting error or file-size issue doesn’t count as filed. If a genuine system outage prevents you from filing on time, file an expedited motion for an extension as soon as the system is restored, and document the outage with screenshots or system notifications.
What Happens If You Don’t File or File Badly
The immediate consequence of failing to file an opposition is that the court may grant the motion unopposed. Judges in most circuits still have an obligation to evaluate whether the motion has merit, but an unopposed motion gets a much friendlier review. On summary judgment specifically, the court can treat any fact you failed to contest as undisputed and grant judgment on that basis.2Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment Failing to respond to a dispositive motion is often case-ending.
Filing an opposition that contains frivolous arguments or false factual claims carries its own risks. Under Federal Rule of Civil Procedure 11, every attorney or unrepresented party who signs a brief certifies that its legal contentions are supported by existing law or a good-faith argument for changing it, and that its factual assertions have evidentiary support.8Legal Information Institute. Federal Rules of Civil Procedure Rule 11 – Signing Pleadings, Motions, and Other Papers If a court finds that a brief was filed for an improper purpose like harassment or delay, or that its arguments are baseless, it can impose sanctions including orders to pay the other side’s attorney fees, monetary penalties paid to the court, or non-monetary directives.
Rule 11 includes a safety valve. Before filing a sanctions motion with the court, the opposing party must serve it on you and give you 21 days to withdraw or fix the problematic filing.8Legal Information Institute. Federal Rules of Civil Procedure Rule 11 – Signing Pleadings, Motions, and Other Papers If you correct the problem within that window, the sanctions motion can’t proceed. The court can also initiate sanctions on its own, though monetary sanctions imposed sua sponte are limited. An aggressive opposition is fine; a dishonest or frivolous one can cost you money and credibility with the judge who still has to decide the rest of your case.