PRINCETON, N.J. — Transparency seems to be the word of the day in a wide array of policy domains. But is greater transparency always good?

Ever since the financial crisis erupted in 2008, there has been a call for "greater transparency" in financial services. The financial-reform law passed by the U.S. Congress last month requires improved transparency from banks and other financial-services firms.

Moreover, thanks to the hard work of Oxfam America and the Publish What You Pay coalition, the law also requires oil and mining companies — both U.S. and foreign — that want to raise capital in the United States to disclose their payments to the governments of countries in which they operate.