Overall, the US Immigration Act of 1990 prohibits foreign crewmen from working as longshoremen while docked in ports in the US. However, it has a few exceptions as explained in the next section. To qualify for D-1, you must be:

1. A foreign crewman loading or unloading hazardous cargoes for which the US Department of Transportation has issued appropriate safety and environment regulations.
2. A foreign crewman who works as longshoreman where this is the prevailing practice. This may be demonstrated by a collective bargaining agreement which covers at least 30% of the longshoremen, and which allows foreign crewmen to engage in such practices.
3. A foreign crewman where the ship on which you work is registered in a country, and is owned by nationals of a country, each of which does not disallow crewmen from performing longshore activities aboard U.S. vessels in its ports.