Tenure is extremely hard to earn. It follows an extended period, usually up to seven years, in which the faculty member's performance in teaching, scholarship, and service to the institution is assessed. At the U of I, fewer than half the junior faculty hired get tenure. The probationary period is well in excess of what is required by most labor union contracts outside higher education and most civil service systems. Just as faculty members must observe these standards individually, so must the tenured faculty uphold and enforce them corporately.
Tenure is more than simple job security.
Faculty members with tenure are subject to regular review. Faculty members are reviewed every semester by their students, annually by supervisors for salary raises, by peers around the country and abroad every time they publish a paper, at least once in great depth after tenure for promotion to the rank of full professor, and whenever the programs they teach in are reviewed. More faculty leave the university after receiving tenure than is generally recognized. Universities often encourage early retirement when productivity has flagged or negotiate termination for misconduct, because these options are more humane and often less expensive than dismissal. Every personnel system requires human judgment, and no system is perfect.