IT'S BEEN five years since James C. Sunday was paralyzed in a skiing accident in Vermont, but the fallout of that lawsuit is still changing the world of skiing.

James C. Sunday, a 21-year-old novice skier, fell, struck his head on a rock and was paralyzed in 1974 in Stratton Mountain, Vt. He claimed that his ski caught a piece of brush just under the surface. The ski area disputed Sunday's claim. In 1977 a jury found the ski area at fault and awarded $1.5 million to Sunday. The Vermont Supreme Court let the verdict stand.

During the legal proceedings, Superior Court Judge Wymm Underwood set a precendent when he determined that the longstanding principle that skiers, as a matter of course, willingly take upon themselves certain risks when they go skiing, especially when they're going downhill, was no longer valid.

Modern ski area technology and marketing techniques have changed all that, according to the judge.

"The ski area operator can no longer, under all circumstances, hide behind the doctrine of voenti no fit injuria (he who consents cannot receive an injury).

"One who partakes in the sport of skiing accepts the dangers that are inherent in it only insofar as they are obvious and necessary," Underwood ruled.

Following the decision, the Vermont legislature, under pressure from ski areas and insurance companies, adopted a new law spelling out responsibilities for skiers and ski areas. The law, in effect, says skiers accepted the risks that were "obvious and necessary," borrowing from Underwood's decision. Ski areas, however, can be held liable for risks that didn't meet those standards.

The most recent outgrowth of Sunday's accident is a new set of laws that affect skiers and ski area operators.

For example, Colorado's recently enacted Ski Safety Act calls for up to $300 in fines for skiers who make a run down a closed slope or trail or ski out of bounds. In the past, such transgressions would have been punished by loss of one's lift ticket. Now, however, they are considered Class 2 petty offenses in Colorado.

Similar laws have been enacted in 17 states, and several others are stuying similar legislation.

The Colorado law, typical of the new wave of legislation, also spells out the responsibilities of the ski area.

"Colorado's new law is a good and important piece of legislation because it establishes the first set of guidelines for the courtrooms," said a spokesman for Colorado Ski Country USA, an organization representing 30 ski areas in the Rocky Mountain State.

"It is also a strike for responsibility -- both for the skiers and the ski area operator," the spokesman said.

For example, Colorado's ski area operators now are required to pad and to mark man-made objects not clearly visible within 100 feet under normal conditions. They also are responsible for providing detailed instructions on how to use the lifts.

The lifts also must be posted to inform skiers which lifts serve only advanced or intermediate slopes, a move designed to keep beginners off the more demanding slopes.

The trails must be clearly marked with their degree of difficulty. Boundaries defining closed and out-of-bounds areas must also clearly be marked under Colorado's new law.

In turn, skiers must ski under control and know their own abilities. Responsibility for collisions with other skiers and clearly marked man-made objects rests solely with the skier -- unless the skier can prove "by a preponderance of evidence" in court that the ski area was negligent.

Skiers leaving the scene of a collision in which an injury results will be committing a Class 2 offense.

Skiing or riding the lifts in an "impaired state" -- drunk or high -- is also punishable by a $300 fine.

Most ski areas reportedly plan to distribute pamphlets and flyers outlining the highlights of the new set of laws.