working CASE statement within a WHERE clause

where_case.sql

DECLARE
    v_filter varchar2(20) := 'All';
    v_count number := 0 ;
BEGIN
    dbms_output.enable(100000) ;
    DBMS_output.put_line('running') ;
    SELECT  count(1) into v_count
    FROM    personnel p
    WHERE   NVL(P.TERMINATED_FLAG,'N') = 'N'
        AND CASE WHEN (v_filter = 'Federal') THEN
                 
                DECODE(P.PERSONNEL_TYPE_ID,1,1,0) 
            WHEN (v_filter = 'Non-Federal') THEN
                DECODE(p.personnel_type_id,1,0,1)
            ELSE
                 1
            END = 1
        ;
    DBMS_output.put_line(v_count) ;
    DBMS_output.put_line('finished') ;

END ;