They have been releasing each season every 6 months or so. Season 8 came to DVD in March, so we should be seeing Season 9 in September or October.
It already is released, as is season 8 and 9.
JAG - 1995 People vs- SecNav 9-14 was released on: USA: 6 February 2004 Japan: 26 May 2008
JAG - 1995 Black Ops 1-17 was released on: USA: 10 April 1996 Japan: 9 February 1997
Season 1 was released to DVD on October 9, 2012. Season 2 was later released to DVD on July 9, 2013.
Season 8 will begin on Sunday, June 30, 2013
JAG Season 6 is being released May 20th 2008, the rest haven't been announced yet.
JAG - 1995 Impact 3-9 was released on: USA: 18 November 1997
JAG - 1995 The Boast 9-9 was released on: USA: 21 November 2003 Japan: 21 April 2008
JAG - 1995 Scimitar 1-9 was released on: USA: 9 December 1995 Japan: 1 December 1996
JAG - 1995 Washington Holiday 2-9 was released on: USA: 28 February 1997
JAG - 1995 Contemptuous Words 5-9 was released on: USA: 23 November 1999
JAG - 1995 Defenseless - 3.11 was released on: USA: 9 December 1997
JAG - 1995 Persian Gulf 9-16 was released on: USA: 20 February 2004 Japan: 9 June 2008
JAG - 1995 Crash 9-15 was released on: USA: 13 February 2004 Japan: 2 June 2008
JAG - 1995 Touchdown 9-5 was released on: USA: 24 October 2003 Japan: 24 March 2008
JAG - 1995 Defenseless 3-11 was released on: USA: 9 December 1997
JAG - 1995 When the Bough Breaks 8-9 was released on: USA: 19 November 2002 Japan: 6 April 2007