A more thorough explanation:

The delegation doctrine is a principle in constitutional law that limits Congress's ability to transfer its legislative power to another branch of government, particularly the executive branch. This principle is based on the separation-of-powers concept.

According to the delegation doctrine, Congress can only delegate its power if it provides an intelligible principle to guide an executive agency in making policy. This means that Congress cannot simply transfer its power to another branch without providing clear guidelines for how that power should be used.

For example, if Congress were to delegate its power to regulate air pollution to the Environmental Protection Agency (EPA), it would need to provide clear guidelines for how the EPA should regulate air pollution. This might include setting limits on emissions or specifying the types of pollutants that should be regulated.

Another example of the delegation doctrine in action is the Affordable Care Act (ACA). In this case, Congress delegated its power to regulate healthcare to the Department of Health and Human Services (HHS). However, the Supreme Court ruled that the ACA violated the delegation doctrine because it did not provide an intelligible principle for how the HHS should implement the law.

Overall, the delegation doctrine is an important principle in constitutional law that helps to ensure that Congress's legislative power is not improperly transferred to another branch of government.