|Media:||Batman: Arkham City|
|Result:||The destruction of many sections of Arkham City and the death of many inmates|
- "I just heard from my dad. He's been summoned to City Hall. Strange is requesting that Emergency Protocol 10 is activated."
"Does Gordon know what Protocol 10 is?"
"Just that it's the worst case security measure."
- ―Oracle and Batman[src]
Emergency Protocol 10, mostly referred to as Protocol 10, was a last-resort/highest security method that was used to control the criminals in Arkham City by using TYGER Security to kill all of the inmates who were contained within.
Protocol 10 could only be activated when approved by the Gotham City Council under one scenario: if the inmates were ever able to get ahold of firearms and appeared to attempt a mass break out. So far, it appeared that not many members of the City Council approved of that method, and hoped that this protocol would never need to be activated. Commissioner James Gordon even voiced his disgust at the measure. Bruce Wayne learned about Protocol 10 when Hugo Strange alluded to it being nearing completion shortly after he ended up incarcerated in Arkham City. It's also implied that the protocol was virtually unknown to most of the inmates, as The Joker, when Batman asked what Protocol 10 was under the belief that Joker was in cahoots with Strange, and Joker denied any knowledge on it.
Once it was deemed that Arkham City had lost its ability to control the weapons that were smuggled into the city (provided by Strange), the City Council approved Protocol 10. Strange devised that plan since the beginning with Ra's al Ghul to gather all of the criminals in Gotham City to one place and just wipe them all out. However, Batman managed to make it to the top of Wonder Tower and stopped it before the plan could be completed. However, at least 22% of the Arkham City inmates were killed or injured during Protocol 10.
Protocol 10 does not appear in the game, but it does heavily factor into the backstory of the game: Specifically, because of the damages caused by Protocol 10 and the populace being horrified at the nature of it, various surviving former inmates (such as Riddler and Two-Face) took the opportunity to sue Gotham City a huge sum of money as compensation and ensure their own freedom, with the Gotham City government being forced to allow them to do so. It was also mentioned by various enemy chatter during the events of the game after they took control of Gotham City thanks to Scarecrow's terror threat on Halloween, where they mused that Hugo Strange with his Protocol 10 actually did Gotham a favor (implying that even they knew they deserved to be killed by Protocol 10).
- If you searched Amusement Mile during the commencement of Protocol 10, you could find dead gang members. It was rumored that those thugs worked for Scarecrow as they wore similar masks to his. What they were doing there was never explained, and their bodies disappeared after Protocol 10 was shut down.
- It appeared that most of the inmates were able to survive by locking themselves in either the Subway or the Sewers.
- During Protocol 10, Strange voiced his plans to use Stage 2 of Protocol 10, by using Metropolis and Keystone City with prisons in a similar fashion to Arkham City. That never happened because Batman stopped Protocol 10.