Amber mentioned that Tammy made 1 (2?) kids stay quiet — can they voluntarily testify for the case? If it's not a single-trial case, could the judge formally summon them to testify in order to discern the truth of the matter, and if so, what's the likelihood of that? The crux of Amber's claim about Tammy relies on second-hand information rather than lived experience, without that first-hand party, neither side is provable nor disprovable, no? But if Tammy has to defend/prove that she wasn't an accomplice to CSA, couldn't that turn into a criminal case, or only if the victims sued for damages?
They could chose to testify, or the Lawyer representing Amber could file to try to have a subpoena granted to compel them to appear(Amber can't do it herself, well, not unless she secretly fatted her way on to the bar with a current license to practice law in OK). It would need to be reviewed and signed by the Judge. The court itself can also issue subpoenas related to the case(in civil court this is more commonly subpoening documents to be provided). There's a small stipend for one day's attendence provided, and millage fee for travel for anyone she subpoened who had to appear.
A subpoena is a serious business Courtorder, it's temporarily taking away some personal liberty to fulfill a civic duty, with serious consequences if you don't show up, kind of like jury duty. It would need to be shown to be both relevant and necessary, and for a judge to agree and sign off to have it issued. It actually potentially is pretty damn important in this situation. Truth is an absolute defense to defamation; and so if Amber's Defense hinges on what she said actually being true, than she'd be dumb not to have her Attorney make sure the people who can prove it's true testify.
I assume these cousin are now fully Adults.
Your question about the questionably provable/disprovable nature of this specific situation sort of loops back to element 5:
the statement was made by someone who should, or could have, known it was false; or taken reasonable care not to make the ststement if they did not, or could not, know it was false.
To apply this here: Amber could, or should, have confirmed with her cousins that this was true before claiming it, because that ubiquitous standard of civil Law, the 'reasonable Person', would know not to say something so damaging/harmful to someone's reputation and/or livelihood unless they absolutely, 100% knew it was true.
(Just remember every element of the tort needs to be met for Tammie to successfully recover.)
I don't know criminal Law well. I don't know what Tammie's obligation may have been to prevent sexual violence she was aware of on her children or how much of an active participant she would have needed to be to be criminally culpable for the abuse committed by another. I do know that there is a crime of enabling child sexual abuse, there was a pretty horrific case just in this August in OK involving multiple children, and an
11 year old girl giving birth to a baby, and enabling child sexual abuse was one of the charges against the mother. The statute is OK Title 21. Crimes and Punishments §21-843.5 (J). I might as well quote it:
J. Any person responsible for the health, safety or welfare of a child who shall willfully or maliciously engage in enabling child sexual exploitation, as defined in this section, shall, upon conviction, be punished by imprisonment in the custody of the Department of Corrections not exceeding life imprisonment, or by imprisonment in a county jail not exceeding one (1) year, or by a fine of not less than Five Hundred Dollars ($500.00) nor more than Five Thousand Dollars ($5,000.00), or both such fine and imprisonment.
OK is also a state where every Adult is a mandatory reporter of child abuse, which has criminal penalties, although those would have long run past the Statute of Limitations. I checked OK's Title 22 of Criminal Procedures, and I couldn't find a specific SoL for failing to report, so I assume it defaults to 3 years or so, It's a misdemeanor in general with fine plus a year max in jail, if you're aware of ongoing abuse over 6 Months, it becomes a felony.
For any actual child sex abuse-related Crimes, not the lack of reporting them, as of 2017 the SoL for charging is before the victim turns 45.
Victims suing civily for abuse as child is difficult if the abuse was not eventually criminally prosecuted, or at least documented somehow, at the time. Not impossible, but difficult. A history of psychiatric care for the lingering symptoms from the abuse, or medical issues caused by the injuries due to the abuse, is helpful in making a case.
I hope that's at least a little helpful in answering your questions.