Edward Fitzgerald, the lawyer representing five retired Gurkhas and the widow of a sixth, said four of the soldiers were barred from entering Britain because their headquarters were in Hong Kong and that they lacked strong ties with this country.
"To say this is to ignore the history of the Gurkhas. And it is to ignore the special debt this country owes to all Gurkhas, past and present, whatever their brigade's location, and whatever their date of discharge," Fitzgerald told the court.
All other foreign soldiers in the British army can settle in Britain after four years' of service anywhere in the world.
About 2,000 Gurkhas are affected by the current rules.
The hearing is expected to last two days, although the result is unlikely to be announced for several weeks.
The Gurkhas have also struggled for years for equal pension rights which, for those who retired before 1997, are about a quarter of the amount paid to those who served after that time.