Media reports say upon arrest last year the three men - two Dutchmen and a Pole - were not given advice on how to challenge the search of their yacht in their native languages.
The lawyers say failing to have done so nullifies the case.
However, according to Radio1 the prosecution claimed that customs staff could search any docked vessel and any challenge could only be filed within 72 hours.
A decision is expected in three weeks.
The three suspects claimed they didn't know about the cocaine on their yacht when they were caught in the Marquesas Islands.
They claimed to have been paid a wage to sail the boat from South America across the Pacific, presumably to Australia.