Serve & Protect

In its original American broadcast, "Serve & Protect" was seen by an estimated 1.91 million household viewers and gained a 0.7/3 ratings share among adults aged 18–49, according to Nielsen Media Research.[1] This was steady in viewership from the previous episode, which was watched by 1.91 million viewers with a 0.7/3 in the 18-49 demographics.[2] This means that 0.7 percent of all households with televisions watched the episode, while 3 percent of all households watching television at that time watched it. With these ratings, Brooklyn Nine-Nine was the second highest rated show on FOX for the night, behind Prison Break, fifth on its timeslot and thirteenth for the night, behind two episodes of Trial & Error, Agents of S.H.I.E.L.D., Imaginary Mary, Prison Break, Fresh Off the Boat, NCIS: New Orleans, Bull, American Housewife, The Middle, NCIS, and The Voice.

"Serve & Protect" received positive reviews from critics. LaToya Ferguson of The A.V. Club gave the episode a "B+" grade and wrote, "The immediate reminder of Veronica Hopkins' personal vendetta against the Nine-Nine isn't a good opening look for the episode though. But it at least ends up being an outlier for the episode, as 'Serve & Protect' isn't just 'The Audit, Part Two.' In fact, this episode steps away from the shenanigans of 'The Audit,' though it's still focused on the Nine-Nine preventing a gross abuse of authority."[3]

Alan Sepinwall of Uproxx wrote, "It's odd: Nathan Fillion's TV career essentially began with the sitcom Two Guys, A Girl and a Pizza Place, where he was a late addition to the cast and very quickly became that show's go-to player, and his two most famous roles on Firefly and Castle drew heavily on his ability to be funny in a dramatic context. Yet when he's popped up on sitcoms lately, they haven't really known what to do with him(*). Community largely wasted both of his appearances as Greendale's head custodian, and this episode of Brooklyn Nine-Nine doesn't seem to have an idea beyond getting him to spoof his role on Castle."[4] Andy Crump of Paste gave the episode a 8.1 and wrote, "The result is still a solid half-hour of sitcom fare with an emotional coda about the other thing that Brooklyn Nine-Nine does really well: Character relationships. Coming from Rosa, an admission of fear that the end of the 9-9 would mean the end of her friendship with Jake is a huge deal, and this, most likely, is why their story enjoys prime real estate in 'Serve and Protect.' It’d just be nice if a little more of that real estate could have been ceded to the other characters, too. (At least the credit sequence is worth all the build-up.)"[5]