Michael Thompson, a 47-year-old executive recruiter from Illinois, expects his former wife to take him to court over vaccinating their two children against Covid-19.
He doesn't trust the vaccine for children, but she wants to follow US health guidelines and have their eight-year-old and 10-year-old inoculated.
It is a clash repeated among separated families across the United States, where widespread vaccine hesitancy has thwarted efforts to end the pandemic despite injections being free and easily available.
"I'm vaccinated, but I don't feel the need for my kids to get the vaccine until it's been proven more," Thompson told AFP. "We don't know the long-term effects for kids."
Thompson says this week's decision by the Centers for Disease Control and Prevention (CDC) to approve the Pfizer vaccine for children aged five and over appeared rushed.
And he is ready for a costly fight against his ex-spouse.
"She's pushing back against me and will likely take me to court, which will cost me between $5,000 and $10,000. But to me it's worth it," he said.
"I'm skeptical (of the vaccine) because it involves my kids. I think I'd be an irresponsible parent if I wasn't."
- Divorce and litigation -
Family attorneys say the CDC decision has opened the floodgates for divorce and litigation.
For Sarah Stark, a 52-year-old divorced therapist from St. Charles, Illinois, approval of vaccines for children is a major relief.
Her 10-year-old daughter Shayna has been homeschooling for the last two years because a history of strokes and a blood clotting disorder puts her at higher risk.
And even though her ex-husband is against getting their daughter vaccinated, Stark is able to because she has sole custody and is responsible for medical decisions.
"He doesn't think the vaccine is a great idea but luckily it's not his decision to make," Stark said.
For many divorcees, things are not as clear cut.
Family law varies state by state, and many parents share custody and medical decisions -- creating a scenario that often must be decided by a judge.
"We saw a few disputes over the vaccines for 12-year-olds, but I think we should expect to see a lot of battles regarding the younger kids because custody battles are usually about younger children," said Holly Davis, a family law attorney with Texas-based firm Kirker Davis.
Davis added that currently about 20 percent of her cases involve vaccination disputes, but she expected that number to increase now that younger kids can be given shots.
- Child's best interests -
Most parenting agreements have a provision requiring parents to try mediation before taking their dispute to a judge, but if that doesn't work, they can end up in court.
A judge will often appoint an independent party, known as a guardian ad litem, to act in the child's best interests.
Chantelle Porter, a family law attorney at A. Traub in suburban Chicago who has been a guardian ad litem, said the vaccination issue was coming up more and more, and judges were looking to science for guidance.
"It's one of those issues that is very hard to meet in the middle," she said.
"Both parents are legitimately concerned about the safety and wellbeing of their children on both sides.
"Every case is an individual case and unique... but I do believe that the court is going to look at the medical guidance from the public health organizations."
Even when couples are still together, vaccinations can bring relationship problems to a head.
"We've had a good amount of divorces over the parents disagreeing over that one issue," said Brent Kaspar, managing partner of Kaspar Lugay in Marin County, California.
"Obviously, they had underlying issues but that pushed them over the edge."
Kaspar added that while he anticipates an uptick in cases reaching the courts, he believes the outcomes will be predictable.
"Here in California, it's been mandated that kids will have to be vaccinated by next year to attend school. The court is going to look at that and say that it's in the best interest of the kid."
The pain and upset of family disputes over vaccines is another sad aspect of a pandemic that has ripped up normal life around world.
"I thought we'd go through this really tough moment in our history as a society and pull together," said attorney Valentina Shaknes, of New York-based Krauss Shaknes Tallentire & Messeri, which has seen a sharp increase in divorce cases.
"So many people got sick, so many died, and I hoped it would have brought out the better qualities in people but instead it brought out the worst."