The blue slip process
A “blue slip” is a form given by the Senate Judiciary Committee Chairman to senators who have a judicial nominee pending for a vacancy in their state. The senators use the blue slip to indicate their approval of or opposition to the nomination, and the Chairman will typically wait until both senators return a favorable blue slip before holding a confirmation hearing.
The blue slip process is not required by law or even senate rule, but is a senatorial courtesy that ensures senators have a say in who serves as federal judges in their home states. When exploited, however, that courtesy can turn into a tool of partisan obstruction, used by senators to unilaterally prevent a vacancy from ever being filled.
Another feature of the blue slip process is its relative lack of transparency. Senators can block a nominee by withholding a blue slip indefinitely without explanation. This maneuver avoids a confirmation hearing, in which the nominee would have the opportunity to publicly defend her record and qualifications.
With this resource, AFJ shines some light on the process by publishing the status of blue slips for each pending nominee, including which senators have returned blue slips, and whether they approve or oppose a nominee.