USA Rugby has provided the following guidance on hurdling:

We have been asked many times if this is Dangerous Play. This is not specified in Law 10.4, and the question cannot be answered with a simple yes or no because there are so many possible variations on the situation.

The short answer is that sometimes it is dangerous and other times it is not, depending on the circumstances. Each play must be judged on its own merit by the referee. Here are some factors to consider when viewing this sort of play:

1. Dangerous Play is not restricted to the specific actions listed in 10.4. That is a list of many of the most common occurrences of Dangerous Play, but the fact that an action isn’t listed does not mean the referee cannot penalize for something deemed dangerous when seen in a game. Here are some actions that aren’t listed in 10.4, but which definitely could be called dangerous:
   • biting an opponent
   • spitting on an opponent
   • punching a teammate
2. There is general agreement that if the defender is directly in front of the ball carrier and standing in a normal tackling position, and the ball carrier goes over the defender like clearing the high hurdles, this is dangerous. Here is an example that should be penalized. There are two reasons:
   • It is dangerous to the opponent because that action brings boots into close proximity of a players face/head.
   • It is dangerous to the ball carrier because if the defender manages to make contact while attempting to tackle, the ball carrier could get flipped and land on his head/neck.
3. Also remember that there are many examples that could be called “hurdling” that are just fine and we see them in almost every game:
   • Jumping over a player who is lying on the ground
   • Jumping to avoid the outstretched arms of a diving tackle attempt from the side.

In conclusion, if it is hurdling a standing (or crouched) defender directly in front of the ball carrier, it is dangerous. If it is something from paragraph three it is most likely fine. For the middle range, the referee needs to judge based on what is presented at the moment.