Congressional Research Service report on new Executive Order restricting agency heads ability to consider earmarks not found in statute can be found as a PDF HERE.
From the report:
"The provisions of Executive Order 13,457 may significantly influence the dynamic that has traditionally governed executive and legislative practice with regard to non statutory earmarks, but the order itself appears to fall within the accepted parameters of presidential authority in the executive order context. Courts have acknowledged a premise upon which the order appears to be based: Earmarks in legislative history documents and other sources that are not anchored in statutory text have no legal force or effect".....
" Congress has options such as expressly including earmarks in the texts of statutes or statutorily incorporating by reference earmarks in legislative history documents. These congressional responses may ameliorate the impact of the order.