There are class actions in Canada and the US, see:

http://arstechnica.com/tech-policy/2014/03/mtgox-class-action-suits-in-us-and-canada-allege-fraud-drag-in-japans-mizuho-bank/

• Gregory Greene et al. v. Mt. Gox Inc et al. (US)

• David Joyce et al. v. Mt. Gox Inc et al. (Canada)