Acte cryptique? Zambrano, welfare rights, and underclass citizenship in the tale of the missing preliminary reference

What kind of right to reside did Zambrano create? Are Zambrano families entitled to rely on the fundamental principle of equal treatment to access subsistence benefits? And when is a question of EU law sufficiently unclear to create an objective duty for the national court of last instance to make a preliminary reference? The UK Supreme Court recently concluded that Zambrano families are not entitled to any particular quality of life or to any particular standard of living – so consigning a potentially vulnerable group of EU national children to underclass citizenship. It did so with surprising certainty, without troubling the ECJ with a preliminary reference. But it is hard to imagine a matter less acte clair, or more in need of clarification and consistency at EU level. There is ample reasonable doubt on the matter, strongly suggesting that the Supreme Court breached its duty to refer. Very little of what the ECJ did say in Zambrano was clear – never mind what it did not say.