"These are the inheritances which Eleazar the priest [and Joshua son of Nun and the heads of the fathers' houses of the tribes of the children of Israel distributed]" (Joshua 19:51). Rabbi Yitzhak said: From where do we know that property declared ownerless by the court is [validly] ownerless? As it is said, "and whoever would not come within three days, according to the counsel of the princes and the elders, all his substance would be forfeited [yehoram], and he himself separated from the congregation of the exiles" (Ezra 10:8). Rabbi Eleazar said: From here — "these are the inheritances which Eleazar the priest and Joshua son of Nun and the heads of the fathers' houses [distributed] by lot to the children of Israel." Now what have the "heads" to do beside the "fathers"? To tell you: just as fathers bequeath to their children whatever they wish, so too the heads [of the court] may apportion to the people whatever they wish.
The Authority of the Court to Declare Property Ownerless
Yalkut Shimoni on Nach 29:5
אלה הנחלות אשר נחלו אלעזר הכהן (יהושע יט, נא). א"ר יצחק מנין שהפקר ב"ד הפקר שנאמר וכל אשר לא יבא בעצת השרים והסגנים יחרם כל רכושו והוא יבדל מעדת הגולה, ר"א אומר מהכא אלה הנחלות אשר נחלו אלעזר הכהן ויהושע בן נון וראשי האבות למאות בני ישראל, וכי מה ענין ראשים אצל אבות, לומר לך מה אבות מנחילין את בניהם כל מה שירצו אף ראשים מנחילין לעם כל מה שירצו: