This last few weeks, we've heard a lot about research conducted by Ziobrowski et. al. (see here and here) on the possibility of informed trading by Senators and Congressmen. Based on abnormal returns earned on their portfolios, it appears that they do use their "inside information" in ways that would be illegal for those not in government service. In case you haven't seen it, here's the 60 Minutes story that brought Ziobrowski's research into the public eye: