A Washington attorney suing the Obama administration for access to alias emails sent by EPA Administrator Lisa Jackson claims that a recent decision by the Justice Department to release thousands of those emails next month contributed to her resigning Thursday. Jackson, in a brief written statement, said Thursday she is leaving the EPA after four years on the job, for "new challenges, time with my family and new opportunities to make a difference." The agency did not offer an explanation. But Chris Horner, a senior fellow at the Competitive Enterprise Institute, said