The basic format for an opinion is a slip opinion. The term refers to a written case disposition issued by the court. At the very least, the content of a slip opinion is the name or caption of the case, the docket number, the date of issuance, the names of counsel representing each party, the author and text of the opinion, and any concurring or dissenting opinions with authors. The court may issue a syllabus as part of the slip opinion. A syllabus is a summary that is not part of the formal opinion and has no precedential value.
Most courts will publish slip opinions to their web sites on the date of issuance, or shortly thereafter. The timeliness of posting depends on the court. Lexis and Westlaw add opinions as quickly as possible, but not always on the date of release. The Supreme Court of the United States is one exception. Opinions by the Court will appear on Lexis and Westlaw within 20 minutes to an hour after public release on the Court's own website.
Slip Opinions are often then paperbound into what are called Advance Sheets before they are bound into a hardcover volume.
U.S. Reports (official)
Finally, Advance Sheets are then bound & distributed as Bound Volumes (as we see in an example above - the US Report volumes, which are the Official U.S. Supreme Court Reports - above).
One aspect of locating opinions on various court web sites is understanding the manner in which they can be arranged. Typically, a court’s web site offers publicly available opinions arranged by date, name, docket number, or some combination of these. This type of arrangement is best used for selecting opinions rather than searching a court's website for relevant documents. Therefore, one generally must have some knowledge of this information in advance of locating an opinion.
Some courts will allow limited (especially compared to what’s available on Lexis and Westlaw) keyword searching. This usually takes the form of searching simple words or phrases. As a consequence, subjective or relational research is difficult at most court-sponsored web sites. Lexis and Westlaw offer far more access points with complex search statements and the ability to limit searches to specific segments or fields within a document. Moreover, Lexis and Westlaw combine various courts into a single database (e.g. all federal courts, all Illinois state courts, Illinois state and federal courts) for broader searches.