The Rule Against Perpetuities Made Simple

The Rule Against Perpetuities (RAP) states: No interest is good unless it must vest, if at all, not later than 21 years after some life in being at the creation of the interest.

Translation: When someone creates a future interest (like a condition in a will or trust), that interest must either vest or fail within a reasonable timeframe — specifically, within 21 years after the death of some person who was alive when the interest was created.

1. Identify the future interest. RAP only applies to contingent remainders, executory interests, and vested remainders subject to open (class gifts). It does NOT apply to vested remainders, reversions, or possibilities of reverter.

2. Find the “measuring life.” Look for a person alive at the time the interest was created whose life is relevant to when the interest vests.

3. Ask: Is there any scenario (however unlikely) where the interest could vest more than 21 years after all measuring lives die? If yes, the interest is void. If no, it's valid.

The Fertile Octogenarian: “To A for life, then to A's children who reach age 25.” Under traditional RAP, we assume A (even if 80 years old) could have another child. That child wouldn't reach 25 until 25 years after A's death — violating the 21-year limit. Interest is void.

The Unborn Widow: “To A for life, then to A's widow for life, then to A's surviving children.” A's “widow” might be someone not yet born, so the final interest could vest too remotely. Void.

The Magic Gravel Pit: Interests tied to events with no time limit (“when the gravel pit is exhausted”) often violate RAP because there's no measuring life.

Many states have reformed or abolished the traditional RAP:

Wait-and-see: Don't invalidate the interest immediately — wait to see if it actually vests within the perpetuities period.
USRAP (Uniform Statutory Rule): Gives interests 90 years to vest instead of using measuring lives.
Cy pres: Courts can reform interests to comply with RAP rather than voiding them entirely.
Abolished: Some states have eliminated RAP altogether (especially for trusts).

RAP questions are designed to test whether you can methodically apply the rule. Don't panic — follow the steps:

1. Identify which interests are subject to RAP
2. Find possible measuring lives
3. Construct the worst-case scenario
4. Determine if the interest could vest too remotely
5. Apply any modern reforms if your jurisdiction uses them

Show your work. Even if you reach the wrong conclusion, demonstrating the correct analytical framework earns significant partial credit.