To step onto the set of “The Good Fight” is to step back into the familiar Chicago world of “The Good Wife.”

On a frigid December Friday in Brooklyn, a crew largely taken from “The Good Wife” huddled in the gray-and-cedar halls of that show’s Cook County Courthouse set. The judge presiding over the courtroom was a recurring character from the original, a mellow liberal played by Jane Alexander. The case in front of her was classically “Good Wife” wonky: Was a surgeon operating on a suspected terrorist on the right side of the Hippocratic oath, or the wrong side of the law?

And audiences won’t have to wait long to see the differences between the original and its spinoff, which comes out Feb. 19. First, there is no Julianna Margulies, who played the lead character, Alicia Florrick, on “Wife.” Second, about halfway through the first episode of “Fight,” Diane Lockhart (Christine Baranski), known for an aplomb as outsize as her statement necklaces, emphatically departs from character. Learning that her savings have been wiped out by a financial scheme, she responds by swearing — and just like that, Diane’s seven-season record of dignified speech is shattered.

Ms. Baranski approved of the choice. “No matter how elegant and gracious a lady you are,” she said, “if you found out, alone in a room, that you just lost all your money, you might” swear.

Now, Diane can curse whenever she wants. “The Good Fight” is being made for CBS’s subscription streaming platform, CBS All Access, which means the show’s creators, Robert and Michelle King, are liberated from the strictures of a broadcast network whose audiences tend to skew older and more conservative than those of its competitors. “Now, the story is allowed to lead,” Ms. King said. “If it needs to be 48 [minutes] instead of 42, if they need to use an expletive, we can do that. It’s not as if the characters are suddenly working down on the docks, but they’re going to talk as you imagine them talking.”

The newfound freedom comes with risks. “The Good Wife” was so intimately invested in its heroine that audiences routinely watched her simply drink in silence. But “The Good Fight” shifts the focus to two former supporting characters and one new one: Ms. Baranski’s Diane is flanked by Cush Jumbo’s Lucca Quinn, who appeared in the final season of “The Good Wife,” and a new character, her goddaughter Maia Rindell, played by Rose Leslie of “Game of Thrones.”

The decidedly more adult spinoff doesn’t seem the most obvious choice to anchor All Access, the network’s answer to services like Netflix and Hulu. The platform currently hosts existing CBS programs, football coverage and “Big Brother: Over the Top,” an expanded version of the long-running reality show. Those offerings don’t seem designed to help the viewer make a seamless transition to an intellectual law saga like “Fight.”

“The Good Fight” picks up one year after the end of “The Good Wife” and is rooted in a single shattering news event, a devastating Ponzi scheme that wipes out Diane’s savings, the same way “The Good Wife” took its inspiration from a string of politicians’ affairs. The man behind the scheme is a close friend of Diane’s, and his daughter, Maia, has just begun working under her. When Diane is invited to join the firm that Ms. Jumbo’s Lucca now works for, she brings Maia with her.

“The thing that really convinced us to do a spinoff was Christine Baranski expressing interest,” Mr. King said. “Then we found this idea, which we liked and we thought felt current. We wanted to explore the idea that family can be a corrupting influence the way we explored marriage as a corrupting influence in ‘The Good Wife.’”

“The Good Fight” also satisfies the Kings’ desire to shed some of the constraints of network television — not just more conservative content standards but the grind of producing 22 episodes per season. (“The Good Fight” will have 10.) Meanwhile, CBS All Access executives needed an intelligent original to try to place the streaming network in the class of other platforms, which have momentum and have gained some critical success.

“This always felt like a show yearning for a little freedom,” said Marc DeBevoise, president and chief operating officer of CBS Interactive. He added that its standards would be closer to those of prime-time shows on cable.

Airing “The Good Fight” on traditional CBS, both parties agreed, was never explored. A slightly edited version of the first episode of “Fight” will also run on the main network, but after that the series will live exclusively on CBS All Access.

The new show will still be similar to “The Good Wife,” even with its different home. Like the original, “The Good Fight” will mine the news for its stories. And the presidential election made that plan feel like a mandate. A coming episode involves a lawsuit that imagines, as Mr. King puts it, “the possible chilling effects of a president who doesn’t seem to shy away from retribution.”

But, as with “The Good Wife,” which took pains to portray three-dimensional conservative characters, viewers should expect varying points of view. “Our writers are not all liberals, and the show doesn’t always follow the characters down their liberal hole,” Mr. King said. “It will take up the issues of pro-lifers very sympathetically. It will ask, ‘What are the ways that alt-righters are not who you think they are?’”

The election results prompted other changes. The day before the vote, Ms. Baranski filmed a scene in which, while packing up her old office, Diane pauses to give a lingering look to a framed photo of her with Hillary Clinton, who is the character’s political touchstone. The scene was later scrapped from the pilot. Instead, the first thing audiences see is Diane sitting at home, in the dark, watching President Trump be sworn in; there’s a dazed look on her face.

It seems to be an appropriate kickoff for a series that has a change of course at its core. “You don’t need to have seen a single second of ‘The Good Wife’ to watch this show,” Mr. King said. “We very much mean to be starting over, and we really feel like the dilemmas for these characters all comment on what’s coming down the line in the world now.”