A Coast Guard monitor on duty the night of the Exxon Valdez disaster testified today he could not have ordered the ship to change course even if he had seen it was headed for a rocky reef. Gordon Taylor said it would have taken the authority of a higher Coast Guard officer to order Joseph Hazelwood to make a course change. However, Taylor said the matter never became an issue because the Exxon Valdez vanished from his radar screen shortly before the accident. Taylor said he struggled to adjust the radar but could not bring the ship back into his viewing range. ``So when you left, it was off the screen, and you didn't see it anymore?'' asked Hazelwood attorney Dick Madson. ``That's correct,'' said Taylor, who went off duty at 11:45 p.m. on March 23. He said he notified the monitor who took over for him that the vessel was outbound but had disappeared from the radar. Madson has maintained that Taylor and Bruce Blandford, the monitor who replaced Taylor at the Coast Guard's Vessel Traffic System on the night of the Exxon Valdez disaster, were not watching the radar screen. Madson says if they had alerted Hazelwood that his ship was moving perilously close to jagged Bligh Reef, the accident never would have happened. Scoring a key legal point, Madson won permission to raise the Coast Guard responsiblity issue after Superior Court Judge Karl Johnstone initially vetoed the tactic. Johnstone reversed himself after considering case law on the issue. But the lawyer was barred from exploring another matter _ whether Taylor and Blandford were using drugs or alcohol on March 24 when the accident happened. Blood and urine tests administered between 15 hours and three days after the grounding showed that Blandford had a blood-alcohol level more than twice the legal limit for driving and Taylor showed a small quantity of marijuana in his system. Johnstone called the marijuana issue ``a red herring'' but said he would reconsider admitting the alcohol test if Madson can show its relevance. Blandford's alcohol reading of .203 was recorded 15 hours after the Exxon Valdez went aground in scenic Prince William Sound. Hazelwood, 43, of Huntington, N.Y., is being tried on a felony charge of second-degree criminal mischief and misdemeanor charges of reckless endangerment, negligent discharge of oil and operating a vessel while intoxicated. The maximum penalty for conviction on all counts is seven years, three months in prison and $61,000 in fines. Prosecution witnesses have said Hazelwood spent much of the day before the accident drinking vodka at a bar in the port town of Valdez. But his shipmates said Hazelwood didn't appear drunk and appeared in command of his ship. The 987-foot tanker, which ripped open on the rocky reef, spilled nearly 11 million gallons of Alaska crude oil, killing thousands of birds and other wildlife and blackening hundreds of miles of rocky coast. Exxon says the cleanup has cost $2 billion so far.