Which doctrine refers to the loss of a right due to inaction over time?

The doctrine that refers to the loss of a right due to inaction over time is the Doctrine of Laches. This legal principle applies in situations where a party fails to assert a claim or right in a timely manner, which can lead to a disadvantage for another party. Essentially, if someone delays taking legal action and that delay negatively affects another person's ability to defend against that claim, the court may deny the claim based on the lack of action.

For instance, if a property owner knows about a potential encroachment but waits several years to act, they may be barred from taking legal action later because the delay could have caused the encroacher to spend money or make improvements under the assumption that the encroachment was acceptable. This doctrine serves to promote fairness and encourage the timely resolution of disputes.