35. Thus, the obligation for the Member States to ensure the effectiveness of the rights that the parties derive from Directive 93/13 against the use of unfair clauses implies a requirement of judicial protection, also guaranteed by Article 47 of the Charter, that is binding on the national court (see, to that effect, judgment in Banif Plus Bank, C‑472/11, EU:C:2013:88, paragraph 29). That protection must be assured both as regards the designation of courts having jurisdiction to hear and determine actions based on EU law and as regards the definition of detailed procedural rules relating to such actions (see, to that effect, the judgment in Alassini and Others, C‑317/08 to C‑320/08, EU:C:2010:146, paragraph 49).
36. In that connection, it should be observed that, according to EU law, the principle of effective judicial protection does not afford a right of access to a second level of jurisdiction but only to a court or tribunal (see, to that effect, judgment in Samba Diouf, C‑69/10, EU:C:2011:524, paragraph 69). Consequently, the fact that the only remedy available to the consumer, as a debtor against whom mortgage enforcement proceedings are brought, is to bring an action before a single jurisdictional level in order to protect the rights derived from Directive 93/13 is not, in itself, contrary to EU law.
48. It also follows that, in Spanish Law, if a consumer and a seller or supplier are parties to mortgage enforcement proceedings, the way in which the proceedings before the national court hearing an objection to the enforcement of the mortgage progress, under Article 695 of the LEC, is contrary to the principle of equality of arms or procedural equality. That principle is, however, an integral element of the principle of effective judicial protection of the rights that individuals derive from EU law, such as that guaranteed by Article 47 of the Charter (see, to that effect, judgments in Otis and Others, C‑199/11, EU:C:2012:684, paragraph 48, and Banif Plus Bank, EU:C:2013:88, paragraph 29).
49. It is settled case-law that the principle of equality of arms, together with, among others, the principle audi alteram partem, is no more than a corollary of the very concept of a fair hearing that implies an obligation to offer each party a reasonable opportunity of presenting its case in conditions that do not place it in a clearly less advantageous position compared with its opponent (see the judgment in Sweden v API and Commission, C‑514/07 P, C‑528/07 P and C‑532/07 P, EU:C:2010:541, paragraph 88).
50. In those circumstances, it must be held that a national procedure for mortgage enforcement, such as that at issue in the main proceedings, is liable to jeopardise the effectiveness of consumer protection intended by Directive 93/13, read in conjunction with Article 47 of the Charter, in that the procedural system reinforces the inequality of arms between sellers or suppliers, as creditors in mortgage enforcement proceedings, on the one hand, and consumers, as debtors subject to mortgage enforcement proceedings, on the other hand, in the exercise of legal claims based on the rights that the latter derive from Directive 93/13, all the more so because the detailed procedural rules giving effect to such claims are incomplete and inadequate for preventing the continued application of an unfair clause contained in the instrument establishing the mortgage on the basis of which the seller or supplier brings enforcement proceedings against the property pledged as security.
51. In the light of these considerations, the answer to the questions referred is that Article 7(1) of Directive 93/13, read in conjunction with Article 47 of the Charter, must be interpreted as precluding a system of enforcement, such as that at issue in the main proceedings, which provides that mortgage enforcement proceedings may not be stayed by the court of first instance, which, in its final decision, may at most award compensation in respect of the damage suffered by the consumer, inasmuch as the latter, the debtor against whom mortgage enforcement proceedings are brought, may not appeal against a decision dismissing his objection to that enforcement, whereas the seller or supplier, the creditor seeking enforcement, may bring an appeal against a decision terminating the proceedings or ordering an unfair term to be disapplied.