Legal Definitions - retroactive law

A retroactive law (also known as a retrospective law or retroactive statute) is a legal rule or statute passed by a legislative body that applies to events, actions, or situations that occurred before the law was enacted. Instead of only affecting future conduct, it "looks backward" to change the legal consequences of past events.

While generally permissible, such laws face significant constitutional scrutiny and are often limited, particularly if they create new crimes for past actions (known as ex post facto laws), impose penalties for acts that were legal when committed, interfere with existing contracts, or take away established legal rights.

Here are some examples:

• Tax Law Change: A state legislature passes a new law on July 1st, stating that all income earned from January 1st of the same year will be subject to a new 1% surcharge. This means the new tax applies to income earned during the first six months of the year, *before* the law was even passed.

  Explanation: This law is retroactive because it applies the new tax rate to income earned during a period that occurred *before* the law's enactment. Individuals who earned income in January through June are now subject to a tax that didn't exist at the time they earned that money.

• Procedural Court Rule: A new rule of civil procedure is enacted on October 1st, allowing for a new type of evidence (e.g., digital forensics from social media) to be admissible in court. The rule specifies that it applies to all ongoing cases, regardless of when they were filed.

  Explanation: This rule is retroactive because it changes the rules of evidence for trials that began or were filed *before* October 1st. Parties in existing lawsuits must now contend with the possibility of this new type of evidence being introduced, even though it wasn't permissible under the rules in place when their case started.

• Professional Licensing Requirement: A state board for medical professionals passes a regulation on March 1st requiring all licensed practitioners to complete an additional 10 hours of continuing education in patient privacy protocols, and states that this requirement applies to the current licensing period which began on January 1st.

  Explanation: This regulation is retroactive because it imposes a new educational requirement for a licensing period that was already underway *before* the regulation was enacted. Professionals who had planned their continuing education based on the old rules now find themselves needing to fulfill an additional requirement for the period already in progress.