In an earlier question I asked whether a married man who sleeps with an unmarried woman is considered Zina and in some jurisdictions was punishable by stoning (Saudi Arabia, Sudan, Iran, Yemen and some states in Nigeria). The answers seemed to indicate that a married man is liable for the death penalty (whether by stoning or some other method).
But, to get around this, a private marriage contract can be performed (Nikah mut'ah) - from my research it seems that this is a carryover from pre-Islamic practices of Arabs, and Shiite Islam does not condone it. Since most of the jurisdictions where stoning occurs are Sunni, though, I want to know what is the legal status of Nikah mut'ah in Sunni countries.