The lack of fairness in asylum responsibility sharing within the EU has been a persistent problem demanding an urgent solution. This article seeks to inform the on-going debate on European solidarity instruments from a constitutional law perspective by taking the principle of solidarity and fair sharing of responsibility pursuant to Article 80 TFEU as its reference point. The article sees this principle as an important mechanism in both the enhancement of fairness in responsibility sharing and the protection of refugees. It argues that the combined reading of Article 80 TFEU and the Charter of Fundamental Rights provides a strong reason to doubt the constitutionality of the Dublin III Regulation, and any decision reforming the asylum regime should take this view into account. Despite its limited enforceability, Article 80 TFEU can play an important role as an interpretation tool, in particular in the assessment of the legality of solidarity instruments.