Was the ancient Roman King ( i.e. rex) elected for eight years?

Question

This is an outgrowth of the discussion here. The rex was indeed elected (or perhaps acclaimed would be better term) by the people at the suggestion of the Senate, as far as I recall but I do not remember term limits - perhaps I am missing something?

UPDATE: Anixx has kindly provided the source for the eponymous hypothesis in his answer below. In my opinion, if that is all the evidence that can be adduced in favour of this hypothesis, then it can be very safely dismissed, for the following reasons:

1. It is not clear where did the number 8 come from to begin with. Why assume a term of 8 years and not 7 or 9? Since there are no references to ancient literary or epigraphic sources in the hypothesis, any guess seems to be just as good.

2. Rome had 7 kings whose reigns lasted 38, 42, 32, 24, 38, 44, 38 and 24 years plus minus 1 year, depending how one counts). Three of the numbers (24,24,32) fit the hypothesis mathematically but the others don't.

3. The theory that the term was 8 years and then somehow became 24 is just that: a theory. I think it fails Occam's razor.

4. The suggestion that Tarquinius Superbus, the last king, was ousted because his formal term of 24 years ran out flatly contradicts everything we know about the end of the kingdom and the establishment of the Republic - the king's ouster was a revolution, a highly irregular proceeding. So his rule of exactly 24 years was actually atypical and is in fact a point of evidence against the theory.

UPDATE #2: I googled a bit to see if Koptev's theory about term limits for the rex has gained any academic currency or has been suggested independently by other scholars - and it seems that it hasn't. For instance, A.A.Schiller in the book Roman Law: Mechanisms of Development explains about the different theories proposed about the extent of the rex's powers but he takes for granted that the position was for life. Here's a quote from p. 137:

There is as much speculation regarding the manner in which the rex was chosen as there is with respect to his powers, since the details must be reconstructed from later reminiscences and reflections of the Republican era. The post was for life, and the successor is traditionally said to have been selected by means of the institution known as interregnum.

UPDATE #3: Just to set the record straight, Koptev's theory has been published by him in a reputable academic journal: (http://www.jstor.org/stable/10.2307/4436788). However, it still seems to not have gained any acceptance or currency - Google Scholar shows just two citations so far, one in another work by Koptev and another in an Italian book. It's in footnote n.31 on p.66 and it begins "No comprendo los argumentos de A. Koptev", i.e. "I do not understand the arguments of A. Koptev".

'Three Brothers' at the Head of Archaic Rome: The King and His 'Consuls' Author(s): Alexandr KoptevReviewed work(s):Source: Historia: Zeitschrift für Alte Geschichte, Bd. 54, H. 4 (2005), pp. 382-423Published

Answer 1

Actually, for 8 years, according to this source:

По-видимому, первоначально обладание царским титулом было ограничено сроком одного поколения в восемь лет. Усыновление путем включения в триаду "братьев" представителей разных поколений позволяло расширить законный срок правления царя до 24 лет. Этот срок стал нормой, за пределы которой можно было выйти, только прибегнув к ухищрениям. Действовавший по закону Анк Марций по истечении 24 лет передал власть Тарквинию и своим сыновьям. Другие цари пользовались формализмом сакрального права, чтобы обойти норму в 24 года. В свою очередь хранители традиций "отцы" воспользовались этим нормативным сроком, чтобы законным образом отрешить от власти Тарквиния Суперба.

It seems that initially possession of the royal title was limited to the term of one generation, i.e. 8 years. Adoption by the way on inclusion into the triad of the "brothers" representatives of different generations allowed to extend the legal term of the rex up to 24 years. This term became a norm, so that it could be surpassed only by machinations. Acting according the law Ancus Marcius after his 24-year term had expired relegated the power to Tarquinius and his own sons. Other kings used the formalism of the sacral right so to surpass the norm of 24 years. In turn, the tradition keepers, the "fathers" used this normative term so to legally dispose Tarquinius Superbus.

http://ancientrome.ru/publik/article.htm?a=1265051084

Uptdate

Можно допустить, что законным сроком правления рекса в некий период римской архаики считались 24 года. Это следует из того, что 24 составляют совокупный срок правления триады братьев по 8 лет. Видимо, некогда в римской истории произошло сознательное утроение статусного времени нахождения у власти путем создания неких ситуаций, в которых братья-наследники не могли быть инициированы как «полновозрастные». В первобытности мужчина получал статус зрелости не только вследствие формального перехода его возрастной группы в соответствующую возрастную ступень, но и в результате успешного завершения серии испытаний, а окончательно закреплял его полноправие ритуал брака. Если создавались условия, при которых «следующий» брат не мог пройти положенные испытания и вступить в брак, обладатель титула рекса как бы терял необходимость его передачи и сохранял его за собой. Брак с «невестой» отстраненного брата закреплял его право. Это могло повторяться несколько раз и избавляло общество от проблем, если братьев недоставало или был четвертый лишний. Кроме того, между династиями городов Лация существовала система сакральных брачных союзом и прочие братья могли становиться рексами на чужбине. Усыновив Тарквиния Приска, Анк Марций включил его в одно поколение с двумя своими сыновьями и таким образом на законном основании передал ему власть после 24 лет правления. Согласно традиции, Тарквиний обязался затем передать власть сыновьям Анка, то есть своим названным братьям, но не сдержал обещания. В этом контексте не случайным выглядит и изгнание Тарквиния Суперба именно после 24 лет правления, когда подошел к концу его формальный срок.

It is possible to assume that the legal term of rule of a rex in a certain period of Roman archaic was considered 24 years. It follows from the fact that 24 constitute the combined term of ruling of a triad of brothers by 8 years. Apparently, sometime in Roman history happened a conscious tripling of statute term in office by creating certain situations in which the brothers-heirs could not be initiated as adults. In ancient times a man earned the status of an adult not only due to formal reaching by his age group of a certain age but also as a result of a successful completing of a series of tests, and finally his full legal status was confirmed by the rite of a marriage. If certain circumstances were created which such that the "next" brother could not pass the test, and marry, the possessor of the rex title lost the necessity to cede the power and kept it with him. Marriage with the bride of the pushed aside brother would wield this right. This could happen several times and freed the society from the problems if the number of the brothers was insufficient or there was a fourth in excess. Besides, between the dynasties of the cities of Latium there existed a system of sacral marriages and other brothers could become reges abroad. By adopting Tarquinius Priscus, Ancus Marcius included him into one generation with two his own sons and this way legally relegated the power to him after 24 years of ruling. According the tradition, Tarquinius promised in turn to cede the power to the sons of Ancus, i.e. his adopted brothers, but did not fulfill the promise. In this context it seems not coincidental the expulsion of Tarquinius Superbus exactly after 24 years of ruling when his formal term came to an end.

http://ancientrome.ru/publik/article.htm?a=1265539577