Which item may not be cited as a precedent?

Technical Advice Memoranda (TAMs) may not be cited as precedent because they are issued by the IRS in response to specific inquiries by taxpayers regarding the tax implications of certain situations. They serve primarily as guidance for the parties involved in the specific case and do not have the same authoritative weight or general applicability as regulations or court decisions. Regulations, including temporary regulations, are designed to have a broader impact and establish rules that govern an entire category of taxpayers, thereby providing a stronger basis for reliance in subsequent cases. In contrast, U.S. District Court decisions can set precedent for future cases, as they are part of the judicial system and contribute to the body of law that courts must follow. This fundamental difference underscores why Technical Advice Memoranda lack precedential value when compared to the other options listed.