A fatwa is issued by a recognized religious authority in Islam. The people who pronounce these rulings are knowledgeable, and base their rulings in knowledge and wisdom. They need to supply the evidence from Islamic sources for their opinions, and it is not uncommon for scholars to come to different conclusions regarding the same issue.
As Muslims, we look at the opinion, the reputation of the person giving it, the evidence given to support it. When there are conflicting opinions issued by different scholars, we must compare the evidence.