In my TPR: Clear and Convincing Evidence, I explained the burden required to terminate a parent’s rights. Even if you can overcome that burden, you still need to show that the termination is in the best interest of the child. Trying to define the best interest of the child is like herding cats; I try to figure it out on a case-by-case basis, and I will not attempt to define it in this post.
However, I have noticed as I try cases that the facts I used to overcome the clear and convincing evidence burden are often enough to show that the termination of parental rights is in the best interest of the child. That coupled with the fact that the folks that are asking for the termination of a parent’s rights generally already have physical custody of the child and are acting as the parent equals a pretty clear decision that termination of parental rights is in the child’s best interest. Then again that is only one of many cats that needs to be herded.
James Fletcher Thompson, Esq., penned a chapter on "Best Interest of the Child" standard in his book South Carolina Adoption Law and Practice: A Guide for Attorneys, Certified Investigators, and Families. This book would be a good starting point for you in understanding the dynamics we call "Best Interest of the Child." Here is a brief review and ordering information.