A number of federal senior judges, some of whom do no judicial work, are in line for substantial pay raises. Administrative records obtained by Associated Press indicate one in five who hold the rank do no work at all, although most of the 305 senior judges have active caseloads. The title of senior judge, created by Congress in 1919, allows federal jurists to sharply reduce their caseload, rather than retire, while still qualifying for active-duty salary increases. Federal judges are appointed for life, although they may choose to resign at any time. Senior judges as a group handle between 10% and 15% of all federal cases. Salary increases for top federal officials, including judges, take effect Feb. 8 unless Congress disapproves.