Tax law is the largest and most technically complex field of American law

Evidence

As a consequence, tax law may well be the single largest field of law, in terms of effort, dollars involved, and the sheer bulk of statutes and regulations, however one meas­ ures it. It is also a field of awesome technicality. The Internal Revenue Code, the key to all of Uncle Sam’s billions, is the longest, most difficult statute in the whole federal armory, as we have seen. — Lawrence M. Friedman and Grant M. Hayden, American Law, 778