Second are the principles of judicial control: principle of conferral and principle of proportionality laid down in Article 5, which requires that our actions are limited to what is essential to achieve the objectives of the Treaties.
Specifically, this means that our measures need to be suitable, necessary and proportionate stricto sensu.2 For an instrument to be suitable, it needs to be able to address the respective risk to price stability. For an instrument to be necessary, we must lack a viable alternative instrument. For an instrument to be proportionate stricto sensu, its expected benefits should outweigh its costs.