"H.R. [House Bill] 115 would require federal courts to consider the murder, attempted murder, or targeting of a law enforcement official or first responder as an aggravating circumstance when determining if a death sentence is warranted for a convicted felon. Based on an analysis of information provided by the Administrative Office of the U.S. Courts about the number of trials the bill would probably affect, CBO [Congressional Budget Office] estimates that implementing H.R. 115 would have no significant effect on the federal budget. Enacting H.R. 115 could affect direct spending and revenues; therefore, pay-as-you-go procedures apply."
Congressional Budget Office: http://www.cbo.gov/