More about U.S. Supreme Court Slip and Official Opinions:
You can read U.S. Supreme Court “slip” opinions online at the U.S. Supreme Court website, but these are neither final nor official opinions. Substantive and typographical edits are made before the opinions are published in the official U.S. Reports. Read the court’s disclaimer on their website regarding these “slip” opinions. (You can read their disclaimer below, i.e. as it appeared today.)
You can find print U.S. Reports volumes (and unofficial print versions) at many, but not all, law libraries. You can also find unofficial print and online U.S. Supreme Court opinions at numerous online legal research sites. Many, but not all, of these sites will update their U.S. Supreme Court opinion files with the final, official U.S. Reports versions.
(Important note: Keep in mind that U.S. Reports volumes are not published until 2 or more years after slip opinions are published, so you will need to rely on unofficial sources for a long while.)
(The Cornell Legal Information Institute (LII) U.S. Supreme Court decision webpage also has lots of useful Supreme Court argument and decision information.)
Disclaimer from the U.S. Supreme Court Opinions webpage:
“’Slip’ opinions are the first version of the Court’s opinions posted on this website. A “slip” opinion consists of the majority or principal opinion, any concurring or dissenting opinions written by the Justices, and a prefatory syllabus prepared by the Reporter’s Office that summarizes the decision. The slip opinions collected here are those issued during October Term 2017 (October 2, 2017, through September 30, 2018). These opinions are posted on the website within minutes after the opinions are issued and will remain posted until the opinions for the entire Term are published in the bound volumes of the United States Reports. For further information, see Column Header Definitions and Information About Opinions.
Caution: These electronic opinions may contain computer-generated errors or other deviations from the official printed slip opinion pamphlets. Moreover, a slip opinion is replaced by a paginated version of the case in the preliminary print, and, subsequently, by the final version of the case in a U. S. Reports bound volume. In case of discrepancies between the print and electronic versions of a slip opinion, the print version controls. However, where the electronic version has been designated “revised,” the electronic version controls to the extent that it differs from the print version with regard to the noted revision. In case of discrepancies between the slip opinion and any later official version of the opinion–i.e., the preliminary print or bound volume version–the later version controls.” [From the U.S. Supreme Court Opinions webpage.]
[Today’s U.S. Supreme Court Opinions’ website disclaimer can also be found at the Internet Archive.]
Hat tip to Law Librarian A. Thornton and the law-lib listserve.