EU harmonisation: is there a problem with restrictions on uses?

My proposal is to provide a comment of recent case T-339/16 (joined with T-352/16 & T-391/16), Ville de Paris and Ville de Bruxelles v European Commission, of 13 December 2018. Although only available in French, Swedish and Spanish, that decision raises important questions related to the incidence of harmonised rules dealing with access to the market of products and substances, on the subsequent restriction in the use of those products and substances at local level. In its decision, the General Court adopts a very extensive interpretation of the mention that Member States ‘shall not prohibit, restrict or impede the registration, sale, entry into service or circulation on the road of vehicles, on grounds related to aspects of their construction and functioning covered by a Directive, if they satisfy the requirements of the latter’, for the sake of its effet utile. According to the General Court, the effet utile of a harmonisation Directive on the approval of vehicles would be at odds with the possibility for a city, in order to improve its air quality, to restrict access of vehicles to its territory, when these vehicles comply with the very latest EU standard. Restrictions would only be valid if they concern general measures ( a one day car-free) or if they target other categories of vehicles. The decision needs to be further analyzed and contextualized as, if it can be welcomed for the reason it provides some clarity on an issue that has been discussed for long in the doctrine, it is potentially disruptive of the balance between environmental law and internal market law, the latter being suddenly given precedence on the former, like back in the old times. Such precedent, if confirmed, could have far-reaching effects on attempts, at local level, to restrict the use of products that comply with provisions guaranteeing, formally, their access to the market. The intention is to assess if that decision on motor-vehicles could be confirmed in appeal but also if it could act as a precedent in other fields, not exactly comparable, such as the restriction of the use of pesticides by cities or regions