A more thorough explanation:

Advance sheets

Advance sheets are collections of recent court opinions that are circulated before they are printed in a reporter or a volume of another reporting system. They are usually published weekly for specific areas like a state or federal district, and they are used by all the major reporters under the National Reporter System.

For example, if a court in California issues a new opinion, it will first be published in the advance sheets for the California courts. These advance sheets will be sent out to subscribers, including the major legal publishers like Westlaw and LexisNexis. The publishers will then use the information in the advance sheets to update their own databases and print the opinions in their own reporters.

Another example is the advance sheets for the federal courts. These are published by the Federal Reporter System and include opinions from all the federal district courts, circuit courts, and the Supreme Court. The advance sheets are used by legal professionals to stay up-to-date on the latest court decisions and to prepare for upcoming cases.

Advance sheets are important because they allow legal professionals to access the latest court opinions before they are printed in official reporters. This means that lawyers, judges, and other legal professionals can stay up-to-date on the latest legal developments and use this information to make better arguments and decisions in their own cases. The examples illustrate how advance sheets are used in both state and federal courts, and how they are an essential part of the National Reporter System.