Your syntax is a little bit off. Use this:
CASE WHEN test IS NULL AND SUBSTR(('99999999' - Tst_Date),1,4) > 2009 THEN 'Medi' WHEN test IS NULL AND SUBSTR(('99999999' - Tst_Date),1,4) < 2009 THEN 'hills' ELSE testEND AS "Phy"