Law & Order - Season 11 Episode 24 : Deep Vote

A woman's murder leads the police to discover the actual target was a reporter who did a story about improprieties in a recent senatorial election. Carmichael can't get the reporter to reveal her sources for a story that contains allegations that the vote was fixed and ballots tampered with, even though the reporter's life is at risk. Without the source, McCoy and Carmichael have a difficult time making a case against the Senator, who they believe has ties to the mob and ordered the hit on the reporter. The case hinges on 2000 missing ballots from the vote that were stolen by the mob. Once the ballots are found, there is a big court battle about whether or not the ballots should be counted. McCoy believes that the ballots will show Benton's motive for ordering the hit, but an appellate court won't allow it, so their case is virtually dead. In the end, McCoy is able to convince the reporter to reveal her source and have him testify against the senator.