Surname law matronym from the name of a parent or parent-in-law; these possibilities are not necessarily open to native Icelanders. Reza Shah Pahlavi ordered Iranians to adopt Western style surnames in place of old Islamic names and titles during his reign. A law in Japan dating from 1896 requires a married couple to have a common surname. Most commonly it was the wife who took her husband's name. In 2011, this law was challenged as unconstitutional on gender equality grounds, but the Supreme Court of Japan upheld the law in 2015. Prussia tasked the implementation of surnames to E. T. A. Hoffmann.
One-name study the etymology, meaning and geographic origin of names, also draw on the macro perspective provided by a one-name study. Many people conducting family history, genealogical or onomastic research may conduct a one-name study of a surname in a given period or locality quite informally. A full one-name study can be daunting, particularly if the surname is very common. Conversely, a rare surname can be difficult to trace. Since such studies are usually conducted by individuals as a pastime, they are generally feasible only when a surname is not used by more than a couple of thousand contemporary people, so that