Gabon 1991
Gabon faced popular pressure for political reform in the early 1990s, as single-party systems faced challenges everywhere. The incumbent head of state initially resisted calls for a national conference but later relented. He maintained considerable control of the constitution making process throughout, however.
In this instance a national conference developed an interim constitution (based heavily on its predecessor), framed guidelines for a new constitution, and empowered an elected assembly to review a draft crafted by the executive but responsive to the guidelines set out by the conference.
The conference had 2000 members. Political parties were not legalized before the conference began. The conference itself authorized political parties to form, but it appears to have represented 75 nascent political tendencies. Initially the incumbent sought to appoint his own supporters to half the seats and objections to this maneuver delayed the start of the meetings. Ultimately the majority of seats were allocated to parties and organizations controlled by the opposition or independents.
The conference lasted about 3 weeks.