Law and Order.

Maybe “White Collar”? That’s a show with an overall light mood. Many funny moments, and I don’t recall much swearing at all. These reviews may help you decide.

Law & Order has those dark moments, but it is a great procedural.
LA Law might be more like you want. I am a fan of Boston Legal, but it has seedy moments.

Ok what about Murdoch Mysteries?

I don’t understand what you mean by “bashing” or sythesizer or dark undertones, exactly.

You might start with older shows such as Dragnet and Adam-12 (the originals, not the remakes/films/reboots).

Hill Street Blues is interesting and worth a look.

The Streets of San Francisco is dramatic in its own ways, but also generally pretty good.

There are a great many British TV drama/police/legal shows, often of quite high quality, too.

There are so many shows, and I don’t know what qualities you’re looking for, nor even really understand what you’re trying to avoid, exactly.

You might try Silent Witness, the BBC series on Amazon Prime. 23 Seasons. The early seasons have more forensic pathology than the later ones which add more physical forensic investigation, and you will wonder if all Brit Pathologists are as hands on as Dr Nikki Anderson, but the show works. It is not overly violent and the language is moderate. As I think of it, the major British series, Morse, Endeavour, Lewis, Midsomer Murders, Prime Suspect, are all more cerebral than violent and generally meet your language requirement. Prime Suspect is the darkest of the bunch.

The TNG episode “Measure of a man”.

Law & Order, the British series.

You have to check out The Practice.

Really well done legal drama by David E. Kelly. Streaming on Hulu and Amazon Prime right now, I think.

It might be worth checking out Broadchurch. It’s a British tv series about a small coastal town where there was a murder of a town member’s son. Solving the case unearths the secrets hidden within many of the residents without being over-the-top, yet the show is riveting.

Perry Mason, the 1950’s series.

The Rookie
Lucifer

The West Wing.

Swear words and dark undertone don’t always go together. You can have a show with totally SFW language and the entire concept is just dark. You really need to clarify which kind of show you want.

The greatest police show ever done was The Wire. But there is plenty of swearing and violence.

Boston Legal.

If you want something realistic, The First 48. But it’s not drama, it’s documenting the first 48 hours of actual investigations.

Oh Boston Legal is a good one, although it’s not a police procedural.

By the way, Boston Legal is a sequel/spinoff from The Practice.

Boston Legal and Lucifer are lighter toned, but they’re comedies (and Lucifer is a supernatural yarn based on a comic book series). If those are appealing there are many others, such as Castle.

@luigirovatti Seems pretty interested in realism, though…

Shetland

You could try A Touch of Frost. Inspector Morse. Midsummer Murders. All great police drama shows in the UK with no swearing, bashing etc.