A legal maxim that means “the law looks forward, not backward.” Article 4 of the New Civil Code provides, “Laws shall have no retroactive effect, unless the contrary is provided.”
Hence, laws are presumed to be prospective unless the intent of the legislature to give them a retroactive effect is expressly declared or is necessarily implied from the language used. In case of doubt, it shall be resolved against retroactivity.
General Rule
The Supreme Court held that Statutes are prospective and not retroactive in their operation, they being the formulation of rules for the future, not the past. Hence, the legal maxim “lex de futuro, judex de praeterito” — the law provides for the future, the judge for the past, which is articulated in Article 4 of the Civil Code: “Laws shall have no retroactive effect, unless the contrary is provided.” (Philippine Deposit Insurance Corporation vs Stockholders of Intercity Savings and Loan Bank, Inc., G.R. No. 181556 December 14, 2009)
Exception
(1) When the law itself expressly provides except:
(a) Ex post facto law
(b) Impairment of contract
(2) In case of remedial statutes
(3) In case of curative statutes
(4) In case of laws interpreting others
(5) In case of laws creating new rights [Bona v.
Briones (1918)]
(6) Penal Laws favorable to the accused