In California, a parent's conviction of a crime can justify modifying child support, provided proof of imprisonment exists. Imprisonment and inability to work can result in a significant change in their income, which can then warrant a modification of the child support agreement. However, it is worth noting that each case is unique, and the court will consider the specific circumstances when determining if a modification is necessary. In these situations, it is recommended that the parent consult with an attorney to discuss their options and ensure that their child continues to receive the support they need.