Though freedom expression is constitutionally protected, in practice there are serious constraints, including “blasphemy” laws in effect in at least some areas.

There are significant differences in the approach to religious courts between mainland Tanzania and Zanzibar. After independence, Tanzania mainland embarked on the process of unification of personal laws. However, Kadhi’s courts remain part of the national judicial system of the island of Zanzibar and Islamic law is predominant in matters of personal status. Many Muslims of Zanzibar regard attempts by mainlanders to reform some aspects of the judicial system as an attack on Zanzibar’s legislative autonomy.

Blasphemy laws are in effect under areas with Sharia law.

There were reports in 2014 that a group of 43 Tanzanian pastors, most former Muslims, were accused of blasphemy for teaching from the Bible to their church members. If convicted of “shaking the faith of Muslims” they could face 14 years in prison.

One Eva Abdulla was charged with blasphemy (accused of desecrating the Koran by urinating on a copy) and in July 2012 was sentenced to 2 years imprisonment. On appeal, January 2013, Abdulla was found not guilty and released.