The blue slip process has been a part of the Senate’s judicial nomination procedure since at least 1917. When a President nominates an individual for a U.S. circuit or district court judgeship, the chairman of the Senate Judiciary Committee sends a blue slip —a form colored blue— to the two Senators representing the nominee’s home state. This form allows the Senators to express their opinions about the nominee.
Positive Response: If a home-state Senator has no objections, they return the blue slip with a positive response, indicating support for the nominee. Negative Response or Withholding: If a Senator objects, they may either return the slip with a negative response or choose not to return it at all. In both cases, this is treated as a lack of support for the nominee, which halts the nomination process.
