Love 'em or love to hate 'em, scrum starts are an integral part of modern derby strategy. Although scrum starts come in many different flavors, here is the setup for the classic jammer line scrum start:
1) One team's blockers line up in a solid wall directly in front of the jammer line.
2) The other team's blockers line up in a solid wall directly in front of the first team's wall.
3) One of those lines have all players starting on a knee.
4) First whistle blows, starting the jam.
5) "No pack" is called.
6) Double whistle is blown, releasing the jammers.
7) Jammers muscle their way through these walls.
8) Rinse.
9) Repeat.
In order to release the jammers during a jammer line scrum start, one team must have all their blockers on a knee (taking themselves out of play) BEFORE the first whistle blows. This legally starts the jam in a 'no pack' situation (technically the jam has started without a formed pack, so no one is illegally destroying the pack), which releases the jammer. The blockers on their knees must IMMEDIATELY stand up and reform the pack, or else they will be penalized for failure to reform. If entire team takes a knee after the jam has already begun, the last blocker to take a knee will be penalized for destroying the pack.
Rules about destroying the pack fall under Section 6.10 OUT OF PLAY PENALTIES.
