Changing child custody represents one of the most complicated areas of family law, according to "Child Custody A to Z" by Guy J. White. The laws of all states establish a high standard to meet in order to change a custody arrangement. That standard requires you to prove a material change of circumstances during an evidentiary hearing in a child custody case, according to Cornell University Law School.
Set forth your general contentions at the start of the evidentiary hearing through your opening statement. The thrust of your statement must be that a material change of circumstances occurred, causing an alteration so significant that the child's best interests are not served through the current custody plan. For example, the custodial parent developed a drug problem, rendering it impossible for him to care for the child properly.
Call witnesses that have direct knowledge supporting the allegations you made during your opening statement. For example, these witnesses include people who possess first hand knowledge of the custodial parent's drug use, or law enforcement officials who have dealt with her.
Present documents supporting your allegations. Documents include medical records, police reports or any other items relevant to the custody issue and the contentions you make.
Listen closely to the statements made by the other parent and her witnesses. Prepare yourself to closely cross-examine these individuals to demonstrate that their statements do not have the same worth and merit as those you made and that were presented by your own witnesses.
Make a closing statement designed to persuade the judge that you met the standard of proving a material change of circumstances.
Request the judge to enter an order changing custody, making you the primary custodian for your child.