On 19 May 2010, the General Court (GC) issued a series of joined judgments on the appeal against fines imposed on six companies by the European Commission (the Commission) in 2004 for their participation in a cartel on the copper plumbing tubes market. The cartel arrangement involved a system of allocation of production volumes and market shares and the setting of targets and prices increases. The Court upheld the fines imposed on four undertakings; Wieland-Werke (€27.84m), Boliden (€32.6m), Outokumpu (€36.14m) and KME (€67.08m), but reduced the fines imposed on IMI and Chalkor to €38.556m and €8.2467m respectively. The Court found that the Commission had not proved to the requisite legal standard that the IMI group participated in the cartel between 1 December 1994 and 11 April 1996. To reflect the reduction in duration, the fine was reduced by 10%. The Court also held that the Commission infringed the principle of equal treatment by calculating the fines imposed on IMI and Chalkor in the same way as the other undertakings even though IMI and Chalkor had not taken part in one set of arrangements between the companies. This was compensated by a 10% reduction in the fines.