Funny you mention legal inaccuracies in a show. I don't know if you made it far enough, but in True Detective season 2, one of the major plot points for Colin Ferrell's character Ray Velcoro is the custody, and legitimacy, of his son Chad. His wife essentially threatens his visitation rights (wants them to be supervised) and if he objects or fights or has any other fits, she'll conduct a paternity test to determine his biological father (pretty sure it's her rapist) Farrell knows this is a strong possibility but would rather not have it proven. In an arbitration meeting, this is all put on the table. In actuality, the law in California says there is a conclusive parentage presumption to a father when his wife conceives while they are married and cohabitating (barring evidence of sterility) under Family Code sec. 7540. That presumption is rebuttable with a blood test, but only if the mother or presumed father files a special motion with the court for a blood test within 2 years of the child's birth (Family Code sec. 7541). In other words, just as we, the audience, might find this situation where Ray raised the kid and can have his parentage unilaterally challenged a decade later, California law finds this unfair too.
Pretty big deal, right?
Anyway, watch Peaky Blinders - it's fookin' awesome.