It happened, when Samuel was old, that he made his sons judges over Israel.
"Sons judges over Israel"  (1 Samuel 8:1).  This cannot mean that they replaced Samuel in any official sense, but that they were deputies appointed by Samuel and empowered to exercise authority that belonged to their father.  It seems that the examples God allowed in the reprobate sons of both Eli and Samuel, and also in the instance of Abimelech the son of Gideon, should have been a sufficient warning to Israel against any system that called for hereditary succession of authority; but Israel did not heed it.