On first watch, which was when it first aired pretty much, "In Loco Parentis" definitely stood out. Sadly not for the right reasons and not in a good way. It was one of quite a number of episodes of Season 19 to not do much for me, in a season where its best episodes were merely very good and the worst pretty weak. While not finding it a terrible episode, just too many things on first watch bothered me and it is a shame because when this show was at its best it was brilliant (which only came in spurts in the latter seasons).
"In Loco Parentis" didn't do much for me on rewatch either, for pretty much the same reasons as before. Again, it didn't strike me as a bad episode and there are worse episodes of 'Law and Order: Special Victims Unit' (including from this season in fact). At the same time, "In Loco Parentis" also wasn't particularly good and is heavily flawed story and character writing wise. When an episode fails in two of the most crucial areas for anything in visual media that is not a good sign.
By all means, there are good things. The production values are suitably slick and gritty, with photography that is reliant on close ups that have an intimacy without being too claustrophobic. The music is didn't come over as too melodramatic or like it was emphasising the emotion too much.
The acting was also mostly fine, some of the best work coming from Peter Scanavino.
A lot on the other hand is wrong with "In Loco Parentis". After liking her a lot in the previous episode, Olivia is back to the sanctimonious judgemental character she was for most of the season. In an episode full of trite, awkward and less than concise dialogue, her preachy, condescending dialogue is particularly borderline cringe-worthy. There is an exception to the acting, and that is Phillip Winchester who continues to fall drastically flat as personality free Stone.
Didn't buy Carisi's lack of objectivity, he doesn't usually have this problem, and is far too personally involved. His advice to Mia was dumb. The case lacks tension and found it mostly predictable and thin, the twist was not a surprise actually for me. The outcome feels very far fetched and incomplete.
Concluding, mediocre and one of the weakest of the season. 4/10.