The UBS Greek text and most translations include for about four hundred and fifty years as the first part of verse 20, but the Revised Standard Version includes these words as the last part of verse 19. The period of four hundred and fifty years is evidently intended to include the whole period from God’s choice of Israel in Egypt to the possession of the land in Canaan, and it is arrived at by adding the four hundred years’ stay in Egypt (Genesis 15.13) to the forty years in the wilderness, and another ten years from the entry into Canaan to the dividing of the land among the tribes (see Joshua 14).
The judges referred to were far from being judges in the contemporary sense of the word; they were spiritually endowed leaders who arose at particular times in Israel’s history and enabled Israel to overcome their enemies. It is not easy to translate properly the word judges since the systems of present-day courts and judicial procedures are so utterly different from what existed in biblical times. In reality these judges were simply leaders or “strong chiefs.” In fact, the closest equivalent to the judges in many face-to-face societies is the term “chief,” since it is the chief who not only gives direction to the activities of the tribe but also judges the internal disputes. It is, therefore, recommended that in many instances the term rendered judges in English be translated simply “chief.”
The expression he gave them judges cannot be readily rendered in a number of languages. Rather, one must say “he caused them to have chiefs” or even “he caused chiefs to lead them.”
The time of the prophet Samuel is distinguished from the period of the judges; Samuel is regarded as the beginning point of a new period in the history of God’s dealings with Israel. Until the time of the prophet Samuel may cause certain complications in some languages since a conjunction such as until always suggests some type of activity, not merely a designation of time. Therefore one may have “until the day the prophet Samuel was leader” or “until the time the prophet Samuel came.” In general, it is important to avoid any such possessive construction as might be suggested by the English preposition of. Most frequently this relationship is expressed in languages as being “time when.”
Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on The Acts of the Apostles. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .