Presumption: classification into may presume, shall presume and conclusive presumptions governs when facts are treated as true. Presumption operates as either presumptions of fact, which are rebuttable inferences from one fact to another, or presumptions of law, which may be rebuttable or conclusive. The law recognises three modes-'may presume' (discretionary rebuttable), 'shall presume' (compulsive rebuttable), and conclusive presumptions-and the practical distinction lies in judicial discretion to raise the presumption, after which the fact is treated as presumed until disproved.