Following the Treaty of Lisbon, national parliaments now have specific powers that allow them to ensure the EU's compliance with the subsidiarity principle. These are known as the 'yellow and orange card' procedures, as set out in Protocol 2. In essence, national parliaments are now empowered to issue 'Reasoned Opinions' when they consider that a proposal breaches the subsidiarity principle, and they have 8 weeks in which to do so. the EU institutions are obliged to take these Reasoned Opinions into account.
In addition, a Reasoned Opinion counts as a 'vote'. Each national parliament chamber has one vote, unless the Member State is unicameral, in which case its chamber has two votes. If more than 1/3 of the votes are cast against the proposal, it must be reviewed. This threshold has yet to be reached, but you can read more about the Reasoned Opinion procedures below:
You can read more about how the Lords EU Select Committee applies the subsidiarity principle and operates the new powers below:
You can read more about the reasoned opinions of the Committee in our document below: