Is it true that a teacher can't engage/attack a shooter from behind during a school shooting that is in progress?

No. Any use of force of any kind that only harms the shooter who is actively engaged in a school shooting (and indeed, even if it caused bodily injury that isn't grave or deadly to someone else who is innocent) is always justified.

You can't shoot someone who is not an ongoing threat to others if they flee, in order to arrest or punish them (e.g. an unarmed shoplifter), but under the leading constitutional case, Tennessee v. Garner, this limitation doesn't apply to murderers and mass shooters anyway, at least if they continue to pose a future threat.

Is it true that a teacher can't engage/attack a shooter from behind during a school shooting that is in progress?

No. Any use of force of any kind that only harms or kills the shooter who is actively engaged in a school shooting (and indeed, even if it caused bodily injury that isn't grave or deadly to someone else who is innocent) is always justified.

You can't shoot someone who is not an ongoing threat to others if they flee, in order to arrest or punish them (e.g. an unarmed shoplifter), but under the leading constitutional case, Tennessee v. Garner, this limitation doesn't apply to murderers and mass shooters anyway, at least if they continue to pose a future threat.

Is it true that a teacher can't engage/attack a shooter from behind during a school shooting that is in progress?

No. You can't shoot someone who is not an ongoing threat to others if they flee, but under the leading constitutional case (Tennessee v. Garner), this limitation doesn't apply to murderers and mass shooters anyway.

Is it true that a teacher can't engage/attack a shooter from behind during a school shooting that is in progress?

No. Any use of force of any kind that only harms the shooter who is actively engaged in a school shooting (and indeed, even if it caused bodily injury that isn't grave or deadly to someone else who is innocent) is always justified.

You can't shoot someone who is not an ongoing threat to others if they flee, in order to arrest or punish them (e.g. an unarmed shoplifter), but under the leading constitutional case, Tennessee v. Garner, this limitation doesn't apply to murderers and mass shooters anyway, at least if they continue to pose a future threat.