HR2391, Intellectual Property Protection Act
Prior to this, distribution of unlicensed fansub animes could be thought as fairly safe since Japanese copyright holders have traditionally turned a blind eye to the fansubbing scene. However, with the possible passing of HR2391, this could dramatically change. If HR2391 is passed, the Attorney General will be endowed with the authority to bring copyright infringers to civil court by themselves, effectively removing the blanket of cover that fansub distributers had.
More info: Wired News: Senate May Ram Copyright Bill