Rules Analysis
Marking Violations:
Double team: If a defensive player other than the marker is within 10 feet of any pivot of the thrower without also being within 10 feet of and guarding (3.E) another offensive player, it is a double team. However, merely running across this area is not a double team.
Merely running means running for the exclusive purpose of reaching the other side. Running with an ulterior motive of interfering with the thrower in any way is not "merely running" and is a double team.
Vision blocking: If the marker deliberately blocks the thrower's vision, it is a vision blocking violation.
Fast count, double team, disc space, straddle, wrapping, and vision blocking are marking violations.
Only the thrower may call a marking violation, and to do so must call out the name of the specific marking violation.
When a marking violation is called, play does not stop. The violation must be corrected before the marker can resume the stall count with the number last uttered before the call minus one (e.g. "stalling one...two...three..." "fast count" "...two...three...").
When a marking violation is called, the marker should immediately stop counting. The defense should then correct the violation and the marker can then resume the count at the appropriate number.
If the defense commits a marking violation after being called for a marking violation during the same stall count (15.A.1) but before the thrower is in the act of throwing, the thrower may choose to either call another marking violation or to treat the marking violation as a general defensive violation (17). To treat it as a general violation, the thrower must call "violation."
The marker may contest a marking violation by calling "violation." This contest is treated as the call of an offensive violation, and the Continuation Rule (17.C) applies.
It is the marker's responsibility to announce if play was affected for the purpose of the Continuation Rule (17.C). Generally speaking, due to 17.L, calls made by another player cannot be said to affect play. However, in limited situations for contested marking violation calls, when the marker diverts their attention away from marking while reasonably and quickly assessing the conditions to the thrower's marking violation call, the marker could determine that play was affected. For example, the thrower calls straddle, and while the marker is looking at their feet to assess their marking position, the thrower completes a throw around the marker. If the marker subsequently contests the straddle because they assessed that they weren't committing a marking violation, they could claim that play was affected and the disc should be returned to the thrower. It is the thrower's responsibility to stop play as soon as possible after the marker makes their call contesting the marking violation (20.F).