The antistes was elected by the great council (the parliament) of the city and held besides this office also a pastorship of one of the main churches.
The antistes had to be an ordained minister. He was the official representative of the church. He was presiding the synod, and the theological examinations of candidates for the office of pastor. His direct rights were very limited, but a man with high leadership capabilities like Zwingli or Bullinger could exert a great influence on the church in this office.
In the late 19th century the title was replaced by other office designations, e.g. church president or president of the church council.
Source: * Article Antistes in the Historical Lexicon of Switzerland (German)