1 et seq. No problem there, you say, as any lawyer should be familiar with these authorities and know how much weight to assign to the cites. However, tax research does have its peculiarities. Hierarchy of Primary Sources Primary sources of law come from a branch of government. The I.R.C. comes from Congress, the legislative branch.
Court opinions come from the judicial branch.
Treasury regulations as well as a slew of other materials come from the IRS, in its role as an administrative function of the executive branch. A hierarchy exists for these primary authorities. After the Constitution, the I.R.C., case law from the Supreme Court, and cases from the taxpayer's own circuit are at the top of the pecking order. Cases from other appellate circuits are only persuasive. Regulations have different weights depending on the type of regulation.