In the Community in The Giver, the Elders have an enormous amount of power. They control every aspect of people’s lives. However, ordinary old people have almost no power at all and are euthanized once they reach a certain age.
There is a regular committee that investigates changes but they seem to have little actual power, as they just deliberate and make suggestions but enact few changes.
The Committee of Elders is another story. They do have power. One task they are assigned is choosing assignments for eleven year olds at the Ceremony of Twelve.
It was a secret selection, made by the leaders of the community, the Committee of Elders, who took the responsibility so seriously that there were never even any jokes made about Assignments. (ch 2, p. 15)
Jonas has seen the Elders watching him, deciding what capacity he had for different jobs.
He knew, too, that the Elders were meeting for long hours with all of the instructors that he and the other Elevens had had during their years of school. (pp. 15-16)
The Committee of Elders also matches men and women to be mothers and fathers in family units (no one actually has his or her own child).
Their Match, which like all Matches had been monitored by the Committee of Elders for three years before they could apply for children, had always been a successful one. (pp. 48-49).
Therefore, the Elders basically control every aspect of life.
Lowry, Lois (1993-04-26). The Giver (Newbery Medal Book). Houghton Mifflin Harcourt. Kindle Edition.