In doing so, monetary policy could be brought into accordance with the required proportionality check as the "Frankfurter Allgemeine Zeitung" writes.
Among other things, Feld and Wieland suggest to check monetary policy by using scientific rules, such as the Oprhanides Wieland rule.
FAZ: "Strengere Regeln für die Geldpolitik"
CEPR Discussion Paper 15320: "The German Federal Constitutional Court Ruling and the European Central Bank's Strategy"