In both theory and practice, different Islamic clerics can issue contradictory, or competing, fatwas. What happens then depends on whether one lives in a nation where Islamic law is the basis of civil law or if one lives where Islamic law has no legal status. It should be noted that many nations in which Muslims make up a majority of the population do not recognize Islamic law as the basis of civil law.
In nations based on Islamic law, fatwas by the national religious leadership are debated before being issued and are decided upon by consensus. In such cases they rarely are contradictory, and they carry the status of enforceable law. If two fatwas are contradictory, the ruling bodies (which combine civil and religious law) effect a compromise interpretation which is followed as law.
In nations that do not recognize Islamic law, religious Muslims are often confronted with two competing fatwas. In such a case, they would follow the fatwa of the leader in the same religious tradition as themselves. Thus, for example, Sunni Muslims would not hold by the fatwa of a Shiite cleric.
See also: Blasphemy, list of Islamic terms in Arabic
External Links to more information
External Links to several anti-Islam sources on fatwas delivering death threats: