Gerontocracy's stability is seen as its strength, which can be more appropriate for institutions that teach principles that do not vary over time. In institutions that have to cope with rapid change, the decreased faculties of the aged can potentially be a handicap in providing effective leadership.
Such a form of leadership is common in communist states in which the length of one's service to the party is held to be the main qualification for leadership. In the time of the Eight Immortals of Communist Party of China, it was quipped, "the 80-year-olds are calling meetings of 70-year-olds to decide which 60-year-olds should retire". For instance, Party leader Mao Zedong was 82 when he died, while Deng Xiaoping retained a powerful influence until he was nearly 90.
In the Soviet Union, gerontocracy became increasingly entrenched starting in the 1970s, at least until March 1985, when a dynamic, young, ambitious leadership headed by Mikhail Gorbachev took power. Leonid Brezhnev, its foremost representative, died in 1982 aged 75, but had suffered a heart attack in 1975, after which generalized arteriosclerosis set in, so that he was progressively infirm and had trouble speaking. During his last two years he was essentially a figurehead. In 1980, the average Politburo member was 70 years old (as opposed to 55 in 1952 and 61 in 1964), and by 1982, Brezhnev's foreign minister Andrei Gromyko, his defence minister Dmitri Ustinov and his prime minister Nikolai Tikhonov were all in their mid-to-late seventies. Yuri Andropov, Brezhnev's 68-year-old successor, was seriously ill with kidney disease when he took over, and after his death fifteen months later, he was succeeded by Konstantin Chernenko, then 72, who lasted thirteen months before his death and replacement with Gorbachev.
Other Communist countries with leaders in their 70s or 80s have included Albania (First Secretary Enver Hoxha was 76 at death), Czechoslovakia (President Gustáv Husák was 76 at his resignation), East Germany (General Secretary and head of state Erich Honecker was 77 when forced out), Hungary (General Secretary János Kádár was 75 when forced out), Laos (President Nouhak Phoumsavanh was 83 at retirement), North Korea (President Kim Il-sung was 82 at death), Romania (General Secretary and President Nicolae Ceauşescu was 70 when executed), Vietnam (President Truong Chinh was 80 at retirement), Yugoslavia (President Josip Broz Tito was 87 at death). On the sub-national level, Georgia's Party head Vasil Mzhavanadze was 70 when forced out, and his Lithuanian counterpart Antanas Sniečkus was 71 at death.
Gerontocracy is also common in religious theocratic states such as Iran, in which leadership is concentrated in the hands of religious elders. Despite the age of the senior religious leaders, however, parliamentary candidates in Iran must be under 75.
Gerontocracy is also well-established in most western democracies. Legislators such as U.S. senators are disproportionately old, and positions of power within the legislatures - such as chairmanships of various committees - are usually bestowed upon the more experienced, that is, older, members of the legislature. For example, Strom Thurmond, a U.S. senator from South Carolina, left office at age 100 after almost half a century in the body, while Robert Byrd of West Virginia was born in 1917 and has served in the Senate since 1959.
Outside the political sphere, gerontocracy may be observed in other institutional hierarchies of various kinds. Generally the mark of a gerontocracy is the presence of a substantial number of septuagenarian or octogenarian leaders—those younger than this are too young for the label to be appropriate, while those older than this have generally been too few to dominate the leadership in numbers. The rare centenarian who has retained a position of power is generally by far the oldest in the hierarchy.
Gerontocracy generally occurs as a phase in the development of an entity, rather than being part of it throughout its existence. Opposition to gerontocracy may cause weakening or elimination of this characteristic by instituting things like term limits or mandatory retirement ages.
Judges of the United States courts, for example, serve for life, but a system of incentives to retire at full pay after a given age and disqualification from leadership for those who fail to do so has been instituted. The International Olympic Committee instituted a mandatory retirement age in 1965, and Pope Paul VI removed the right of Roman Catholic Cardinals to vote for a new Pope once they reached the age of 80 (which was to limit the number of Cardinals that would vote for the new Pope, due to the proliferation of Cardinals that was occurring at the time and is continuing to occur.).
On the other hand, gerontocracy may emerge in an institution not initially known for it. The Church of Jesus Christ of Latter-day Saints was founded by Joseph Smith, Jr., a 24-year-old man, who in 1835 constituted the first Quorum of the Twelve Apostles with members ranging in age from 23 to 35. Once it was established that succession to the church presidency derived from longest tenure in an office held for life, the hierarchy aged markedly, and with the growth of the church the age at which officials were named to the highest bodies continued to rise. Six church presidents have held office past the age of 90, and until his death in 2008 the church was actively led by Gordon B. Hinckley.
In the fantasy series the Wheel of Time by Robert Jordan, The Kin, a group of women that at some point failed to become Aes Sedai, do not hold any value in the strength of someone in the One Power, as opposed to Aes Sedai, and only defer to age.
In the Frederik Pohl novel Search the Sky, the main character Ross, encounters a planet with a gerontocracy masquerading as a democracy. It uses phrases such as "Old Heads Are Wisest" and gives the population the right to choose who is oldest.