 In 2003, a proprietary Unix vendor and former Linux distribution vendor called SCO alleged that Unix intellectual property had been inappropriately copied into the Linux kernel, and sued IBM, claiming that it bore responsibility for this.Several related lawsuits and countersuits followed, some originating from SCO, some from others suing SCO.However, SCO's allegations lacked specificity, and while some in the media reported them as credible, many critics of SCO believed the allegations to be highly dubious at best.