Excerpt from Understanding the Racing Rules of Sailing
by Dave Perry,

The Slam Dunk
The Slam Dunk is an aggressive and often contentious tactic used upwind by S to gain control over P. It is more commonly used in match and team racing than in fleet racing. The relationship between S and P is rapidly changing in this maneuver such that the rules analysis gets quite complicated. However, the last sentence in rule 17.1 (On the Same Tack, Proper Course) is designed to greatly discourage S from using this tactic.

See the illustration below for a detailed analysis of the "Slam Dunk."