As military rule ended in Nigeria a decade ago, an Islamic legal system was swept into place on a wave of popular support in the country’s desperately poor and mostly Muslim northern states. It has turned out in a way few expected. The draconian amputation sentences warned of by human rights activists and the religious oppression feared by Christians have mostly not come to pass. But neither has the utopia envisioned by backers of sharia law, who believed politicians’ promises that it would end decades of corruption and pillaging by civilian and military rulers. The people are still poor and miserable, residents complain, and politicians are still rich. How the battles over sharia play out could have effects beyond Nigeria, a nation pivotal to West Africa’s stability and viewed by the United States as key to stopping the spread of religious extremism in Africa. American Secretary of State Hillary Rodham Clinton is expected to discuss the issue with Nigerian leaders on a visit to the country this week.