The Protocol on the application of the principles of subsidiarity and proportionality enables national parliaments to take a decision according to the formula of subsidiarity during the review of proposals of the Commission. Following the Protocol, the Commission must review its proposal when national parliaments via one third of the votes allocated to them issue a reasoned opinion stating why the national députés consider that the draft in question does not comply with the principle of subsidiarity (‘yellow card’). If more than half of the votes of the national parliaments issues such an opinion, the Commission is obliged to not only reconsider its proposal, but the Parliament and the Council must each decide by a specific vote on the respect of subsidiarity (‘orange card’).
Initially it has been questioned whether national parliaments would be interested in this process. An assessment of the current situation shows however that there has been a shift. According to the 2012 report of the Commission on the relations between the European Commission and national parliaments, the latter have addressed 663 opinions to the Commission in 2012, of which 509 dealt with legislative texts. Among them, only 70 related to 23 Commission’s proposals constituted issues regarding explicitly subsidiarity. More importantly, the year 2012 witnessed the first use of the ‘yellow card’ concerning the proposed regulation called “Monti II”. Based on the legal basis of Article 352, this proposal drew the consequences of the Laval and Viking case law in determining the relationship between the fundamental right of workers to take collective action, including industrial action and strike action, and the freedom of provision of services. It stated that these freedoms respected the right to strike and to take collective action. It also required the establishment of extrajudicial mechanisms to solve conflicts especially in case of the ones of a cross-border nature. More importantly, in case of judiciary regulation, it called upon national courts to assess, following the proportionality principle, if a collective action would not go beyond the objectives pursued. It was thus about a codification of the jurisprudence of the Court of Justice of the EU.
For the first time, the necessary threshold of reasoned opinions to initiate the ‘yellow card’ procedure was reached. Twelve reasoned opinions representing nineteen votes were addressed to the Commission, so the threshold set at one third of the votes was exceeded by one. In fact, the objections were rather related to the question of EU competence than subsidiarity as such. Most reasoned opinions opposed the European Union to regulate the right to strike. These opinions were based on the fact that Article 153 TFEU excludes the right to strike from the Union’s competences in the social domain. These opinions therefore assessed that such a prohibition could not be circumvented via the flexibility clause of Article 352 TFEU. In addition, some parliaments assessed that the proposed measure consisted of a harmonization which is prohibited under Article 352, paragraph 3, in areas where the Treaty excludes it. Basically, instead of a dispute on subsidiarity, the national parliaments rejected the Court’s argument that Article 153 cannot help to solve interactions between fundamental freedoms and the right of collective action. However, according to the Court, if a regulation under national jurisdiction conflicts with a fundamental freedom, the matter falls within the scope of Union law. This does not mean that the EU can regulate the right to strike, but it is competent to intervene to ensure that the right to strike does not jeopardize the functioning of the internal market. Yet some parliaments, including the French Senate, wanted to suspend this functional interpretation of Union’s competences based on the internal market.
The Commission re-examined the proposal, as stipulated in the ‘yellow card’ procedure, and concluded that the principle of subsidiarity was respected. It justified the use of Article 352 by the prohibition contained in Article 153, but followed the position of the Court that the interactions between the right of collective action and fundamental freedoms fall under the scope of Union law’s application. When it comes to a situation which member states cannot solve independently, given its cross-border nature, European interference is justified under the principle of subsidiarity. Nevertheless, the Union has withdrawn its proposal for political reasons, considering that it would not receive the needed political support in Parliament and Council. This precedent shows that, in the future it will be difficult to act against the objections represented by one third of national parliaments’ votes because it will be unlikely to get a majority in Council and possibly in Parliament. The “Monti II” case has an important symbolic value as first use of the ‘yellow card’. Yet this hasn’t altered the situation significantly, since – with the absence of regulation – it leaves the scope open to the application of the Court of Justice jurisprudence. The absence of positive integration leaves room for uncertainty of negative integration. This precedent also shows that the approach of national parliaments on subsidiarity is far from following a strict legal line. Instead, the invocation of subsidiarity is used as an instrument to fight a legislative proposal that is deemed inappropriate whatever the real reason is.
 Report of 30 July 2013, COM(2013)565 final.
 After the Monti II proposal (12 reasoned opinions), the proposal for a regulation on the Fund for European Aid to the Most Deprived elicited the second highest number of reasoned opinions. Eight other proposals elicited three reasoned opinions each. This trend seems to confirm the varying political interests of national Parliaments, which follow different priorities when choosing Commission proposals to be scrutinised in the context of the subsidiarity control mechanism and apply different criteria when assessing compliance with the principle of subsidiarity. This means that coordination among them remains a challenge (source: Annual Report 2012 on Subsidiarity and Proportionality, 30 July 2013, COM (2013) 566 final). In the list of the most active chambers, the Swedish Riksdag comes first (twenty reasoned opinions), followed by the French Senate (seven reasoned opinions) and the German Bundestag (five reasoned opinions).
 Proposal for a Council Regulation on the right to take collective action in the context of freedom of establishment and freedom to provide services COM/2012/0130 final.
 Case law of 18 December 2007, C-341/05.
 Case law of 11 December 2007, C-438/05.
 In a bicameral system each parliament has one vote, in a unicameral system the parliament has two votes. The breakdown was as follows: SE Riksdag (2 votes), DK Folketing (2 votes), FI Eduskunta (2 votes), FR Senate (1 vote), PL Sejm (1 vote), PT Assembleia da República (2 votes) LV Saeima (2 votes), LU Chamber of Deputies (2 votes), BE House of Representatives (1 vote), UK House of Commons (1 vote), NL Tweede Kamer (1 vote) and MT Kamra tad-Deputati (2 votes).
 This is a classical approach. For example, when the Treaty contained no provision on data protection, the directive on this issue was adopted not because the Union has acknowledged a specific expertise in data protection or human rights, but because the differences between national laws prevented the proper functioning of the internal market.
 French Senate’s proposal for a European Resolution on reasoned opinion of 25 April 2012:”Article 153, paragraph 5, of the TFEU categorically excludes the right to strike from the competences that may be subject to an action by the Union, a fortiori, harmonization. The argument provided by the European Commission according to which the Court of Justice of the European Union’s cases law shows that Article 153 does not apply to the right to strike, is not admissible. It does not mean that the right to take collective action is excluded from the scope of Union law; it consists in depriving the effectiveness of this limitation clause since almost no field can be considered as abstruse to European Union law. The use of Article 352 hasn’t sufficient grounds.”
 According to the statement of the spokesman of the Commission at Europaforum.lu “The Commission can confirm that it has initiated the process of withdrawal of the proposal. The legal assessment of reasoned opinions elicited by national Parliaments as part of the ‘yellow card’ did not lead to the conclusion that the principle of subsidiarity has been violated. But the Commission followed the political debate on the draft regulation. This is an assessment of policy responses in the European Parliament and the Council which led the Commission to conclude that the proposal would not receive the necessary political support for its adoption. A vote of approval by the European Parliament and a unanimous agreement of the Member States would have been needed.”