December 12 can fall on any day of the week.
August 12, 1976 fell on a Thursday.
December 12, 1990 was a Wednesday.
December 12 1947 was a Friday.
December 12 1958 was a Friday.
December 12 2010 was a Sunday.
Tuesday
January 12 1976 was a Monday.
March 12, 1976 was a Friday.
December 12, 1972 fell on a Tuesday.
December 12, 1765 fell on a Thursday.
December 12 1979 was on a Wednesday.