Writing a legal opinion comes down to four disciplines done in order: isolate the exact question, build the facts and the authority underneath it, choose a confidence level that honestly reflects how settled the law is, and structure the document so the reader reaches the conclusion without working for it. If you want to know how to write a legal opinion that holds up to scrutiny, most of the work happens before you draft a sentence.
Pin Down the Question First
The most common failure in opinion practice is a question that was never tight enough to answer. “Is this deal legal?” is not something you can opine on. “Does the proposed lease assignment require landlord consent under the existing agreement, and if so, can the landlord unreasonably withhold it?” is. Push back on vague requests until the question is specific enough to research and specific enough that the answer will actually help the client decide something.
Run a conflict check before you accept the work. The professional conduct rules in effect across U.S. jurisdictions require reasonable procedures to identify conflicts in litigation and non-litigation matters alike, and failing to maintain those procedures will not excuse a violation.1American Bar Association. Rule 1.7 Conflict of Interest: Current Clients – Comment If a conflict exists and informed written consent cannot resolve it, decline.
Confirm you’re competent to take the matter on. Rule 1.1 requires the legal knowledge, skill, thoroughness, and preparation reasonably necessary for the representation.2American Bar Association. Rule 1.1: Competence If the subject is outside your experience, associate with someone qualified or pass on the engagement.
Build the Factual Record
Gather the facts before you touch a legal database. The opinion is only as reliable as the factual foundation beneath it, and a fact that collapses later takes the conclusion with it. Separate the facts that bear directly on the legal question from background context, and verify independently anything you can confirm without relying on the client’s word alone. Read every document you plan to reference. If you haven’t reviewed it, don’t opine on it.
Research With Primary Authority and Verify It’s Still Good
Start with primary sources: statutes, regulations, constitutional provisions, and the governing documents the client is bound by. For a federal tax question, that means the Internal Revenue Code and Treasury Regulations. For a corporate governance issue, the relevant state entity statute and the client’s charter and bylaws. Appellate case law shows how those authorities have been applied to facts like yours.
Secondary sources, including treatises and law review articles, help you orient in unfamiliar territory and point to primary authorities you might otherwise miss. They explain the law; they don’t make it. The opinion has to rest on primary authority.
Then run every case through a citator before you cite it. Decisions get reversed, overruled, distinguished, or undercut by new legislation, and an opinion built on a case that is no longer good law is the kind of mistake that produces malpractice claims. The same discipline applies to statutes and regulations: confirm you’re reading the current version and that no recent amendment has touched the provisions you rely on.
Pick a Confidence Level That Matches the Law
Opinions carry different degrees of certainty, and the standard you choose tells the reader how much risk remains. Three levels dominate professional practice, especially in tax and securities work.
- A “will” opinion is the highest confidence level, generally understood to reflect at least 90% certainty. Use it when the law clearly supports the position and there is little room for reasonable disagreement.
- A “should” opinion reflects roughly 70% or greater confidence. The weight of authority favors the position, but some interpretive uncertainty remains.
- A “more likely than not” opinion reflects greater than 50% confidence. The analysis rests on the pertinent facts and authorities, but the outcome is genuinely uncertain. This standard is common in tax penalty defense.
The SEC has addressed this directly for registered offerings: if uncertainty prevents counsel from issuing a “will” opinion on a material tax consequence, counsel may issue a “should” or “more likely than not” opinion but must explain why a higher-confidence opinion cannot be given and describe the degree of uncertainty.3U.S. Securities and Exchange Commission. Legality and Tax Opinions in Registered Offerings: Staff Legal Bulletin No. 19 (CF) Picking the right level is not hedging. It communicates risk honestly.
Structure the Opinion So the Reader Can Find the Answer
Formats vary by practice area and firm custom, but most opinions include the same components. Identify the addressee and the date, because the opinion speaks as of a specific day. State the purpose and scope, so the reader knows what question is being answered and what is deliberately outside the frame. List the documents and facts you reviewed, including the client representations you accepted without independent verification. Set out assumptions and qualifications. Present the legal analysis. State the conclusion. Sign, with your firm and bar admission jurisdiction.
Keep each legal issue in its own section. If the opinion answers three questions, the reader should find each analysis and each conclusion on its own. Mixing issues together buries the answer.
Choosing an Analytical Framework
Two frameworks keep the reasoning transparent. IRAC moves from issue to rule, applies the rule to the facts, and ends on the conclusion. CRAC leads with the conclusion, then walks back through rule and application before restating it. CRAC fits a sophisticated reader who wants the bottom line first. IRAC fits analysis complex enough that the reader needs to follow your logic before the conclusion will make sense.
Write Assumptions, Qualifications, and Reliance Limits Carefully
Every opinion rests on stated assumptions. Common ones include that signatures on reviewed documents are genuine, that copies are accurate reproductions of originals, and that the client’s factual representations are complete and truthful. If an assumption fails, the conclusion may fail with it, and the reader needs to know what they’re relying on.
Qualifications carve out what the opinion does not address. An opinion on a loan agreement might exclude title or lien priority issues, environmental compliance, or the laws of jurisdictions outside the writer’s license. These aren’t weasel words. They stop the reader from relying on the opinion for questions it was never built to answer.
Reliance limits control who can treat the opinion as authoritative. A legal opinion may be relied upon by its addressee and by any other person expressly authorized to rely on it.4American Bar Association. Risk Management for Legal Opinions: Limiting Who May Rely on Your Opinion Letters Naming the parties entitled to rely keeps the opinion from drifting into the hands of strangers who might later sue. In a debt securities transaction, for example, reliance is typically extended to the trustee and collateral agent and excluded for individual noteholders, who are represented collectively through the trustee.
Draft With Candor and Supporting Citations
Write for the actual reader. A general counsel can handle legal terminology with minimal translation. A board member or business executive needs legal concepts translated into practical consequences. “The non-compete is likely unenforceable because the geographic restriction is broader than any court in this jurisdiction has upheld” lands better than a paragraph on reasonableness doctrine.
Every analytical conclusion needs a supporting authority. If you say a provision is enforceable, cite the statute or case that establishes the standard. If a transaction triggers a filing requirement, point to the regulation. An opinion without citations is a letter with letterhead.
Candor is required. Rule 2.1 obligates a lawyer acting as an advisor to exercise independent professional judgment and render candid advice, even when the conclusion is not what the client wants to hear.5American Bar Association. Rule 2.1: Advisor The same rule allows you to factor in economic, social, and practical considerations relevant to the client. A sound opinion acknowledges weaknesses in the client’s position and addresses counterarguments. Ignoring unfavorable authority doesn’t erase it.
Watch for the Mistakes That Sink Opinions
A recurring set of errors sinks otherwise competent work:
- Inadequate factual investigation. Signing without verifying entity status, without reading referenced documents, or without confirming exhibits are complete and attached.
- Recycling old forms carelessly. Starting from a prior opinion and failing to scrub references to a different borrower, bank, or deal. Common enough that it is worth a dedicated review pass.
- Opining outside your jurisdiction. Issuing opinions on the law of states where you aren’t licensed. Limit the opinion to federal law and the law of your licensed jurisdiction, and say so.
- Failing to negotiate the opinion request. Signing whatever the other side submits because the deal is closing. Deal pressure is not a reason to issue an opinion you aren’t comfortable with.
- Skipping the authority check. Citing cases or statutes without confirming they remain good law.
- Overstepping scope. Opining on title, lien priority, or environmental compliance when those weren’t part of the engagement. If you didn’t investigate it, don’t opine on it.
Specialized Rules for Securities and Tax Opinions
Certain practice areas layer their own requirements on top of the general framework. If your opinion falls into one of these, the standards below apply in addition to everything above; if it doesn’t, the baseline is enough.
When a company registers securities for public sale, federal regulations require a legality opinion from counsel as an exhibit to the registration statement.6eCFR. 17 CFR 229.601 – (Item 601) Exhibits For equity securities issued by a U.S. corporation, the opinion must confirm the shares will be legally issued, fully paid, and non-assessable when sold. For debt securities, it must state that the obligations will be binding on the issuer. The SEC has clarified that these opinions may not carry unacceptable qualifications, conditions, or assumptions, and counsel must file a written consent under Section 7 of the Securities Act. A tax opinion in a registered offering must identify each material federal tax consequence, state the author’s opinion on each, and set out the basis. If the author cannot opine on a material consequence, the opinion must say so, explain why, and discuss alternatives and risks for investors.3U.S. Securities and Exchange Commission. Legality and Tax Opinions in Registered Offerings: Staff Legal Bulletin No. 19 (CF)
Any practitioner giving written advice on a federal tax matter is subject to Circular 230. The advice must rest on reasonable factual and legal assumptions, the practitioner must reasonably consider all relevant facts and circumstances, and the practitioner must make reasonable efforts to identify and ascertain the facts relevant to each tax matter. You cannot rely on a taxpayer’s representations when doing so would be unreasonable, and you may not take into account the possibility that a return will not be audited. Reliance on another practitioner’s advice must be reasonable and in good faith; it is not reasonable to rely on someone you know or should know is not competent or has a conflict.7eCFR. 31 CFR 10.37 – Requirements for Written Advice Violations can bring monetary penalties and other sanctions.
Final Review Before You Send
Proofread for grammar, typos, and formatting. Verify every factual statement against the documents you reviewed. Confirm every citation is accurate and current. Check that the conclusion answers the question you were asked, not a close relative of it.
Then read it from the reader’s side. Can they find the answer without rereading the analysis? Do the assumptions and qualifications make sense without inside knowledge of opinion practice? Does every section earn its place, or are passages lingering from the template you started with? An opinion no one can act on is one that failed, however thorough the research behind it.