The U.S. Supreme Court has addressed and attempted to clarify the issue of Jones Act "seaman" status. In Chandris v. Latsis, - Chandris v. Latsis, U. S., 115 S. Ct. 2172, 132L.Ed.2d314(1995) - the lower court had held that a worker could qualify as a Jones Act seaman if he was "either permanently assigned to a vessel or performed a substantial part of his work on a vessel". The Supreme Court reversed, holding that a seaman must have a connection to a vessel in navigation in terms of both its duration and its nature.

No specific finding was made as to whether Latsis was a Jones Act seaman, but the court set forth the following guidelines for determination of seaman status:

Those working aboard a vessel for the duration of a voyage in furtherance of the vessel's mission are not necessarily seamen.
Jones Act coverage depends not on the place where the injury is inflicted, but on the nature of the seaman's service, his status as a member of the vessel, and his relationship as such to the vessel and its operation in navigable waters. A distinction must be made between sea-based workers and land-based workers who have only a transitory or sporadic connection to a vessel in navigation.
Land-based maritime workers do not become seamen because they happen to be working aboard a vessel when they are injured, and seamen do not lose Jones Act protection where the course of their service to a vessel takes them ashore.
In evaluating the employment-related connection of a maritime worker to a vessel in navigation, courts should not employ a "snapshot" test for seamen status , inspecting only the situation as it exists at the instant of injury; but rather, the total circumstances of an individual's employment must be weighed to determine whether he has a sufficient relation to the vessel. Thus, a worker may not oscillate back and forth between Jones Act coverage and other remedies depending on the activity in which the worker is engaged while injured.

The essential requirements for seaman status are:

An employee's duties must contribute to the function of the vessel or to the accomplishment of its mission;
A seaman must have a connection with a vessel in navigation (or to an identifiable group of such vessels), that is substantial in terms of both its duration and its nature;
The duration of a worker's connection to a vessel and the nature of the worker's activities, taken together, determine whether a maritime worker is a seaman because the ultimate inquiry is whether the worker in question is a member of the vessel's crew or simply a land-based employee who happens to be working on a vessel at a given time.