This implies, among other things, that if the ECB is faced with two policy options that are equally effective with respect to its primary objective, it must choose the one that is better aligned with the EU’s economic policies. Purchases of corporate bonds vividly demonstrate this principle.
Given the high priority that European policymakers attach to climate protection, if purchases of two bond portfolios are deemed to provide a similar degree of monetary accommodation, but one of them has a lower carbon footprint, then the ECB should purchase the portfolio with the lower footprint.