Joseph Sinde Warioba (born September 3, 1940) served as Prime Minister of Tanzania from 1985 to 1990. Furthermore, he served concurrently as the country's Vice President. He has also served as a judge on the East African Court of Justice, and as chairman of the Tanzanian Constitutional Review Commission since 2012. Warioba was chosen to lead the Commonwealth Observer Group in the April 2007 Nigerian elections. He gave a positive assessment of the elections, deeming them to be progress while also saying that there were irregularities.