LONDON -- A legal battle over a child's best interests and the rights of its anguished parents has thrown two British families into turmoil.

A young couple was this week cleared of abusing their baby three years ago -- but may never regain custody of the child, who was taken from them and adopted by another family.

Karrissa Cox and Richard Carter, both now 25, took their 6-week-old to a hospital in 2012 when it suffered bleeding in the mouth. Doctors saw bruising and what they thought were fractures, and Cox and Carter were accused of child cruelty and neglect.

Prosecutors dropped the charges this week after experts questioned whether the child had fractures, and diagnosed rickets, vitamin D deficiency and a blood disorder that causes people to bruise easily.

The child -- whose name and gender have not been revealed -- was initially put into foster care, but while the criminal case was ongoing, a family court ruled that it should be adopted.

Cox and Carter say they plan to appeal, though legal experts say the odds are against them.

"We just want our child back," Cox told ITV news. "We are going to appeal this adoption and we are going to fight to get our child back, every step of the way."

Lois Langton, a partner in the family department at London law firm Howard Kenendy, said it was "an unbelievably tragic story" that should never have happened.

She said it is highly unusual in cases of alleged abuse for an adoption to go through before the criminal case has been resolved. But recently there has been a "huge desire to speed everything up in the family courts," where proceedings can drag on for years.

"Speed was not in the child's interest," she said.

Langton said the child, now about 3, "does not remember any other parents" than its adoptive family.

"The longer they go through the appeals process, the harder it becomes to remove the child from the adoptive parents," she said.

Michael Turner, lawyer for Cox and Carter, said Friday that "these innocent parents have been spared a criminal conviction and a prison sentence for a crime they never committed."

"Their life sentence is that they are likely never to see their baby again."