( CNN ) -- A Navy helicopter whipped the waves as the U.S. Coast Guard closed in on the suspected drug traffickers abandoning their homemade submarine off the coast of Ecuador . U.S. Navy and Coast Guard personnel approach a sinking drug sub about 200 miles off the coast of Ecuador . The men did n't go down with the ship , but any evidence did . When authorities confront `` drug subs '' on the high seas , trafficking busts turn into rescue operations , the Coast Guard says . In the past , no evidence meant no case . But a new law aims to change that . The Drug Trafficking Vessel Interdiction Act of 2008 was signed into law in September . The statute makes it a felony , punishable by up to 20 years in prison , to travel through international waters in the vessels , technically known as self-propelled semisubmersibles . Drug subs come in several forms and are built of fiberglass , wood and steel in the swamps along the west coast of Colombia , under the cover of heavy foliage , Coast Guard officials say . Despite costing upwards of $ 2 million , the vessels are generally abandoned at sea after delivering their cargo , according to the Coast Guard . But with cargo values estimated to range from $ 200 million to $ 400 million , the investment pays big dividends . They are hard to see , rising less than 2 feet ( little more than a half-meter ) above the waterline , and can be 80 feet ( 24 meters ) long , large enough to move 10 to 15 tons ( about 9,000 to 14,000 kilograms ) of cocaine at a time . Federal officials estimate drug subs now transport about one-third of all cocaine that moves by sea from South America to the United States . Detecting the vessels is nearly impossible for law enforcement even with advancements in sonar , radar and infrared technology . Catching them involves a combination of good intelligence and luck , and often relies on the use of helicopters . Once caught , suspected smugglers often `` scuttle , '' or sink , the subs , sending both vessel and cocaine to the bottom of the sea . Though maritime law requires drug-trafficking crews in distress to be rescued , the crews are usually released without prosecution , because of a lack of physical evidence . But under the new law , no physical evidence is necessary . Just being on board a drug sub is proof enough . A dozen suspected cocaine smugglers taken into custody between December 31 and January 8 could be among the first prosecuted under the new law . The cases are expected to develop over the next several weeks , according to a spokesman for the U.S. attorney 's office . Besides a stiff prison sentence , suspects could be fined up to $ 1 million if convicted . The suspects were taken in three separate drug sub incidents in which alleged traffickers sank the vessels and cargo . The first came December 31 , some 200 miles ( 322 kilometers ) off the coast of Ecuador . Another vessel was stopped January 7 about 550 miles off the coast of Ecuador . The most recent arrests were made January 8 , about 150 miles offshore from the Ecuador-Colombia border . `` As we go through the first prosecutions associated with this , we are actually kind of paving new ground here on how it is we have to prepare cases , '' said Adm. Thad Allen , commandant of the U.S. Coast Guard . `` I think you can see where the planned operation of one of these vehicles on the high seas is a crime in and of itself significantly , significantly simplifies the prosecution for us , '' he said . The new law , while untested , appears likely to pass constitutional muster . `` This is a unique statue probably born out of the frustration of federal officials trying to prove criminal activity on part of the drug traffickers , '' said Robert Silbering , former special narcotics prosecutor for New York . `` This just throws another obstacle in the way of traffickers . '' `` The idea here is we do n't have to catch you with the drugs ; if we catch you with the vessel , we are going to prosecute you for that , '' said David A. Moran , a professor at the University of Michigan Law School . But as the law evolves , so do the traffickers ' tactics , Allen said . `` The latest adaptation , '' he noted , `` is the introduction of liquid cocaine and smaller loads on faster boats hugging the coastline and trying to avoid us by staying in the territorial sea of another nation . ''
Three ` ` drug vessels '' intercepted in past two weeks , Coast Guard says . Crew members sank all three , along with others , officials say . Lack of physical evidence often prevents criminal prosecutions . New law makes it a felony to travel through international waters in the Caribbean .