A more thorough explanation:

The Jensen Doctrine is a principle in maritime law that states that a state statute cannot be applied in a maritime case if doing so would "work material prejudice to the characteristic features of the general maritime law or interfere with the proper harmony and uniformity of that law in its international and interstate relations."

For example, if a state law requires a certain type of safety equipment on a boat, but that equipment is not required under general maritime law, the Jensen Doctrine would prevent the state law from being applied in a maritime case.

Another example would be if a state law imposes a different standard of liability for maritime accidents than what is established under general maritime law. The Jensen Doctrine would prevent the state law from being applied in a maritime case because it would interfere with the uniformity of maritime law.

In summary, the Jensen Doctrine ensures that the general maritime law remains consistent and uniform across different states and countries, and prevents state laws from interfering with this consistency.