An opinion letter is an opinion by a lawyer on a particular issue of law. It is most often used in connection with business transactions. An example illustrates the use of an opinion letter. Suppose Bank is making a loan to XYZ Corporation. XYZ Corporation will be required to sign a loan agreement, a security agreement, a promissory note and other documents in order to obtain the loan. Bank wants to make certain that XYZ Corporation is authorized to enter into these transactions. Bank will require that XYZ Corporation provide Bank with a legal opinion letter (i.e., a letter from XYZ Corporation’s lawyer addressed to Bank) stating that, in the lawyer’s opinion, XYZ Corporation has taken all necessary steps to authorize signing the loan agreement and all of the other loan documents, and that these documents are binding obligations of XYZ Corporation, enforceable in accordance with their terms. Bank’s receipt of this opinion letter will be a condition to making the loan. No opinion letter, no loan. Legal opinion letters are required in virtually all large business transaction. You will also sometimes see opinion letters in connection with litigation, although less frequently.