Egypt's interim, military-appointed government has announced the country will enter a month-long "state of emergency." That may seem drastic to outside observers, and in some ways it is, but such provisions have been intermittently common in Egypt -- and bitterly disputed -- since 1967.

In fact, Egypt's last month-long state of emergency was declared just last January, when since-ousted President Mohamed Morsi declared a curfew and gave police the power to arrest and detain at will in the cities of Port Said, Suez and Ismailia.

Prior to that, from 1967 (when Egypt and other Arab states lost the "Six-Day War" against Israel) until 2012, Egypt's broad "emergency law" gave the president and police sweeping powers to arrest "perceived threats to the country's stability," including anti-government protesters and opposition parties. While the law was theoretically intended only for times of crisis, Hosni Mubarak activated it for almost a 20-year period -- from 1981 to 2012 -- when he was president. Here's the Post's Ernesto Londono explaining it in 2011:

Critics say that through it all, the real aim has been control. In a country ostensibly heading toward open elections, it is a vital issue. Under the emergency rules, political gatherings of more than a handful of people can be held only with the state's permission, and the government has allowed few new parties to organize or opposition groups to gather ...
When activated, the law allows security forces to detain people without warrants, circumvents traditional criminal courts to keep suspects detained for years, permits interceptions of communication and restricts gatherings such as protests.

That made the law a lightning rod in Egypt's 2011 revolution, and its expiration in 2012 was hailed as a victory by human rights groups and the U.S. State Department.

Of course, we don't know how similar this new state of emergency will be to the old emergency law, and ultimately, a "state of emergency" in Egypt  means what the government wants it to. It does not, however, bode well for the Muslim Brotherhood. They have historically been the group that suffered most under the emergency law.