"What law makes me liable?" ... try the US Constitution, Amendment XVI quoted here for your convenience. The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several states, and without regard to any census or enumeration. The IRS Code is a collection of laws passed to support and implement the above. Granted The Code could use some serious "simplification" and possibly changing to a different system, such as "The Fair Tax" idea which is circulating now. (I'm not advocating this new system but it could possibly work.) But as to Judge Learned Hand's quote, my suggestion is for people to learn as much about the current Code as it applies to their individual situation and quit over paying their taxes. Tax "evasion" is illegal but using the current Code to your advantage is perfectly legal and expected.