129It follows from the case-law that it is for the Commission to prove not only the existence of the cartel but also its duration (see Joined Cases T-25/95, T-26/95, T-30/95 to T-32/95, T-34/95 to T-39/95, T-42/95 to T-46/95, T-48/95, T-50/95 to T-65/95, T-68/95 to T-71/95, T-87/95, T-88/95, T-103/95 and T-104/95Cimenteries CBR and Others v Commission [2000] ECR II-491, paragraph 2802 and the case-law cited). More particularly, as regards proof of an infringement of Article 81(1) EC, the Commission must prove the infringements which it has found and adduce evidence capable of demonstrating to the requisite legal standard the existence of the facts constituting an infringement (see, to that effect, Baustahlgewebe v Commission, paragraph 97 above, paragraph 58; Case C-49/92 PCommission v Anic Partecipazione [1999] ECR I-4125, paragraph 86; and Groupe Danone v Commission, paragraph 78 above, paragraph 215). Any doubt in the mind of the Court must operate to the advantage of the undertaking to which the decision finding the infringement was addressed. The Court cannot therefore conclude that the Commission has established the infringement at issue to the requisite legal standard if it still entertains any doubts on that point, in particular in proceedings for annulment and/or variation of a decision imposing a fine. Indeed, in the latter situation, it is necessary to take account of the principle of the presumption of innocence, which is part of the fundamental rights protected in the legal order of the European Union and has been enshrined in Article 48(1) of the Charter of Fundamental Rights of the European Union (OJ 2007 C 303, p. 1). Given the nature of the infringements in question and the nature and degree of severity of the ensuing penalties, the principle of the presumption of innocence applies in particular to the procedures relating to infringements of the competition rules applicable to undertakings that may result in the imposition of fines or periodic penalty payments (see, to that effect, Case C-199/92 PHüls v Commission [1999] ECR I-4287, paragraphs 149 and 150; see also, to that effect, Groupe Danone v Commission, paragraph 78 above, paragraphs 215 and 216). It is thus necessary for the Commission to produce sufficiently precise and consistent evidence to support the firm conviction that the alleged infringement took place (see Groupe Danone v Commission, paragraph 78 above, paragraph 217 and the case-law cited).