One thing you can do is ...

create procedure myProc

(@status char(1))

AS

BEGIN

set nocount on;

IF (@status ='B')

BEGIN

/* run this code with no filtering by the field 'active'*/

END

ELSE

BEGIN

SELECT /* your columns

..., etc... */

WHERE active = @status

END

END/* proc */

I have a hunch the engine can produce multiple query plans in this instance. Is this correct?