A twelve year old can't, on their own, petition the court or make a decision to move to Germany. Only a parent can make that decision for a child.
A custodial parent is required to provide, at least, 30 days notice of an intended relocation. A noncustodial parent can object to the relocation, and petition the court to "enjoin," or prevent, the relocation. If the relocation is disputed, the custodial parent must show that the move will not substantially impair the child's relationship with the other parent and that the move provides an independent benefit to the child - not necessarily the same as a benefit to the custodial parent.
The above response has been provided for general guidance on matters of interest only and is not intended as a legal advice. No attorney-client relationship has been created between the reader of this response and The Law Office of Karen M. Holman, PLLC.
Answered on Jan 09th, 2012 at 1:53 PM