CASA stands for Court Appointed Special Advocate.
GAL stands for Guardian ad litem.
Duties of the CASA/GAL are defined by RCW 13.34.105.
CASA/GALs are appointed by judges to represent the best interest of children involved in the dependency court system. The CASA/GAL researches the child's situation by talking with the child as well as others who play a significant role in the child's life. The CASA/GAL writes a report to the court for review hearings with information about the parents’ progress in services and an update about the child, the child’s expressed wishes, as well as what the CASA/GAL believes is in the child’s best interest.
See RCW 13.34.105