Why would the Court be strict on the express policy grounds mentioned in Article 36 and yet allow for implied – additional – grounds of justification at the same time?
The explanation behind this apparent paradox is that Article 36 was originally designed against the backdrop of the international market model within which it was to apply to discriminatory national measures. But once Article 34 was seen – after Cassis – to cover non-discriminatory measures, the Court was caught in a dilemma: on the one hand, it wished to recognise that the expansion of the material scope of Article 34 had to trigger a – simultaneous – expansion of the potential grounds of justification; yet, on the other hand, that expansion could not take place within Article 36 because that might invite the Member States to use the new grounds also for discriminatory measures and thereby undermine the Court’s tough stance here. The way out of this dilemma was daring but ingenious: the Court simply deposited a second justificatory route but only for those measures that fell outside the international market model.
What's "the international market model"? The author didn't define it.
What were "those measures that fell outside the international market model"?
What was the "second justificatory route"?
With the emergence of the federal model in Cassis, the Court thus began to exempt obstacles to the free movement of goods that were
necessary in order to satisfy mandatory requirements relating in particular to the effectiveness of fiscal supervision, the protection of public health, the fairness of commercial transactions and the defence of the consumer.186