Contrary to the claims by Sovereign Citizens, a judge who has not taken his oath of office still is a de facto judge, at least at the Federal level.
See for example: Ramos v. Pyramid Tribal Court, Bureau of Indian Affairs, 626 F. Supp. 1582 – Dist. Court, D. Nevada 1986. See also McDowell v. United States, 159 US 596 – Supreme Court 1895
Judge de facto is defined as:
One who holds and exercises the office of a judge under color of lawful authority and by a title valid on its face, though he has not full right to the office, as where he was appointed under an unconstitutional statute, or by an usurper of the appointing power, or has not taken the oath of office.
Black’s Law Dictionary 5th Ed. 755. A judge who in complete good faith continues to hold court beyond the term for which he was assigned may be considered a de facto1583*1583 judge. Oklahoma Transp. Co. v. Lewis, 177 Okl. 106, 58 P.2d 128, 129 (1936).
The proper action to challenge the Judge would be through a Quo Warranto action, which in case of the federal government, needs to be filed in DC and can be filed only by someone who has a direct interest in the office and who has been granted leave by court or by the Attorney General at his own discretion. What is particularly hilarious is that most common law jurisdictions have adopted a de facto officer doctrine.
A officer becomes a de facto officer under four circumstances: (1) by exercising his or her duties without a known appointment or election, but under such circumstances of reputation or acquiescence as were calculated to induce people, without inquiry, to submit to or invoke his or her action, supposing him or her to be the officer he or she assumed to be; (2) where the official exercises his or her duties under color of known and valid appointment or election, but fails to conform to some precedent, requirement, or condition, such as to take an oath, give a bond, or the like; (3) under color of a known election or appointment, void because the officer was not eligible, or because there was a want of power in the electing or appointing body, or by reason of some defect or irregularity in its exercise, such ineligibility, want of power, or defect being unknown to the public; or (4) under color of any election or an appointment by or pursuant to a public unconstitutional law, before the same is adjudged as such.
Source: SIERRA CLUB v. CASTLE COOKE HOMES HAWAI INC 25, Supreme Court of Hawai‘i.
Good luck arguing in Hawaii…