The Collaborative International Dictionary of English v.0.48:

Status in quo \Sta"tus in` quo"\ (st[=a]"t[u^]s [i^]n` kw[=o]"),
Status quo \Sta"tus quo"\ (st[=a]"t[u^]s kw[=o]").[L., state in
   which.]
   The state in which anything is already. The phrase is also
   used retrospectively, as when, on a treaty of peace, matters
   return to the status quo ante bellum, or are left in statu
   quo ante bellum, i.e., the state (or, in the state) before
   the war. The form status quo is in most common use.
   [1913 Webster]