From Lawrence del Brok (1247) to 1999, a rigid constitutional barrier existed without exception: the Attorney General was, by definition and necessity, a Commoner — an MP at the Bar of the House, reachable and accountable to elected representatives. The "Blue Book" parliamentary records confirm this for seven centuries. A forensic audit of modern appointments reveals a stark party split: every Conservative Attorney General in the modern era — Dominic Grieve, Jeremy Wright, Geoffrey Cox, Michael Ellis, Suella Braverman, Victoria Prentis — was an MP. Labour alone has broken the rule, appointing Peers: Baron Williams of Mostyn (1999), Baroness Scotland, and now Baron Hermer.

The legality of a person's presence and function in Parliament is defined entirely by the Writ they receive from the Monarch. Two distinct instruments exist: the Writ of Attendance — issued to the Attorney General, commanding them to serve and advise the House as a neutral assistant (the "Servant's Summons") — and the Writ of Summons, issued to a Peer, commanding them to sit and vote as a partisan member (the "Master's Summons"). Baron Hermer holds both simultaneously. Voting records for 2024–2026 confirm he has exercised "Master's Power" in partisan Lords divisions. One cannot be commanded to be a neutral assistant and a voting partisan member at the same time. The Writ of Summons effectively cannibalises the Writ of Attendance, rendering the Attorney General's Servant function a legal nullity.

House of Commons Standing Order No. 63(1) governs the participation of Law Officers in Public Bill Committees. It grants the right to deliberate and move motions specifically to Law Officers who are "Members of the House" — that is, MPs. A Baron cannot enter the Commons Committee floor. The result is a constitutional black hole: the very official tasked with certifying the legality of legislation is procedurally barred from the chamber where that legislation is debated and scrutinised. The 1614 Commons Resolution — which refused to seat an Attorney General precisely because they were a Servant of the King — confirms this principle has ancient authority. The office is occupied by someone who is mechanically ineligible to perform its primary statutory function.

The Attorney General's oath of office requires service to the Sovereign "without let for any gift, or other cause." This is a negative covenant of the highest constitutional order. Using the 1755 Samuel Johnson Dictionary — the definitive baseline for interpreting the oath's language — "cause" is defined as "a side; a party; a faction." The Labour Party Whip is, by that definition, a permanent contractual loyalty to a private factional cause. By accepting a Peerage alongside a party whip and voting in partisan divisions, the incumbent has lodged what Johnson called a "bias" — "the weight on one side of a wheel which turns it from the straight line." Serving as the Crown's impartial law officer while subject to a party whip constitutes what the investigation terms a "Feat of Perjury" — the Peerage acting as a shield against discovery of the very bias the oath forbids.

Erskine May's first edition (1844) — never repealed by Parliament — establishes the Attorney General as a prosecutorial servant at the Bar of the House. The nemo judex in causa sua principle (no one may be a judge in their own cause) exposes the fatal flaw in the "Partisan Peer" model. If the Labour Party were accused of systemic wrongdoing before the High Court of Parliament, Baron Hermer would face a three-way constitutional collapse: as Attorney General he is expected to be the impartial prosecutor; as a Labour Peer he is politically aligned with the accused; and as a member of the Lords he would be among the judges. The e-petitions investigation (HC 235) further confirms that petitions raising the legality of the AG's own office have been administratively intercepted before reaching the floor of the House — a verified constitutional fraud.