Legislative proceedings in the Siambr

Published 01/12/2020   |   Last Updated 23/12/2020   |   Reading Time minutes

Legislation is usually considered at least once in Plenary during the course if its passage through the Senedd. Some types of subordinate legislation, Bills of Senedd Cymru, and consent motions relating to UK Parliament Bills are all considered at least once in the Siambr.

Subordinate legislation

Acts of the Senedd and Acts of the UK Parliament enable Welsh Ministers to make more detailed legislation, known as secondary or subordinate legislation.

The affirmative procedure

A small proportion of the most important subordinate legislation is subject to approval (the affirmative procedure) and has to be formally approved by the Senedd in Plenary before it takes effect.

The negative procedure

Most Subordinate Legislation is subject to annulment (the negative procedure). This means that the legislation will come into power unless a Member tables a motion against it (a “motion to annul”) within a certain deadline. If the Senedd agrees to the motion tabled against the legislation, the legislation does not progress.


A Bill is a proposal for a new law, or a proposal to change an existing law that is presented for debate before the Senedd. Bills are normally considered in both committee and in Plenary. Most Bills will go through the following stages of consideration:

  • Stage 1 – consideration and agreement of the general principles of the Bill;
  • Stage 2 – detailed consideration of the Bill and any amendments tabled by a committee of Senedd Members;
  • Stage 3 – detailed consideration in Plenary of the Bill and any selected amendments;
  • Stage 4 – passing the final text of the Bill.


Legislative Consent Motions

When the UK Parliament wishes to legislate on a subject which has already been devolved to the Senedd, convention requires it to receive the consent of the Senedd before it may pass the legislation in question. Such consent is given by the agreement of a Legislative Consent Motion (LCM) in Plenary.