The commissioner only has the authority to punish minor breaches of the code, such as an accidental delay in reporting a financial interest. ³⁰ House of Commons, Procedural Protocol in respect of the Code of Conduct, 24 February 2023, HC 1084, p. 11  This usually involves an MP making an apology to the Commons or correcting the record.

In cases of more serious wrongdoing, the commissioner sends their report to the Commons select committee on standards. The Standards Committee is made up of seven MPs and seven non-parliamentarians (or ‘lay members’) who are appointed by MPs following nomination by the House of Commons Commission. Non-voting lay members were introduced in 2012 and were intended to make the standards process more robust in the wake of the expenses scandal; they were given the power to take part in committee votes in 2019.

The Standards Committee determines whether there has been a breach of the code and, if so, what sanctions ought to be imposed. The committee can impose some sanctions of its own authority, such as requiring a written apology or requiring an MP attend training. More serious sanctions – like suspending an MP – must be approved by the House of Commons itself. MPs agreed in October 2022 that votes on the committee’s reports would be taken without debate or amendment – a change intended to avoid a repeat of the controversial vote on the report into the conduct of Owen Paterson.

Since 2022, MPs have been able to appeal any decisions of the Standards Committee to the Independent Expert Panel, which is made up of eight members drawn from outside of parliament and appointed by MPs, again, following nomination by the House of Commons Commission. In these cases, the panel makes their report to the House of Commons directly. The panel has heard (and dismissed) three such appeals since gaining this power.