Henry Stern makes interesting point

Under the existing City Charter, matters to be placed on the November ballot must be approved by the City Clerk sixty days before the election. This year that date was September 5. The mayor waited until that date had passed to announce publicly that he sought re-election and exemption from the charter. The delay precluded the public from voting on the issue this year.

City Council Votes Itself A Third Four-Year Term, Overriding Two Referenda

The City Charter itself is a lengthy document, and is properly subject to amendment by the City Council. Probably a two-thirds vote, rather than a simple majority, should be required to amend the city’s basic governing document. But in any event, Section 38 of the Charter forbids the Council to amend those parts of it which deal with duties and powers of the mayor, the length of terms of elective office. In general, it prohibits the Council from mucking around with the election process.

This charter was adopted in 1989 by referendum. It protected the people’s right to vote on issues submitted to them. The charter did not mention term limits, which did not exist at the time, it therefore did not specifically prohibit the Council from repealing or amending them without a referendum, although it clearly would have done so if the possibility had been considered.