In the law
, a presumption
of a particular fact can be made without the aid of proof in some situations. The types of presumption includes a rebuttable discretionary presumption, a rebuttable mandatory presumption, and an irrebutable or conclusive presumption. The invocation of a presumption will normally shift the burden of proof
from one party to the opposing party in a court trial. Presumptions are sometimes categorized into two types: presumptions without basic facts, and presumptions with basic facts.