Matthew J. Ruff Appellate Practice Law Blog on Lawyers.com

In California, the answer is yes. In general, a juvenile court may only confine a minor to the maximum time available up to the age of 25 years of age at the California Youth Authority, now called the Department of Juvenile Justice.  However, under Welfare and Institutions Code section 1800, a person considered "physically dangerous to the public" because of "mental or physical deficiency, disorder, or abnormality," may be held for two year periods  on a indefinite time period.  Thus a person could be held beyond the age of 25.
The factors that is used in determining whether to seek an extension of time of the person include the underlying facts of the case, the wards behavior while incarcerated as well as a psychological risk assessment.  However, it appears the underlying facts of the case that led to the commitment to the California Youth Authority appears to a major influence for prosecutors in making that decision. In other words, the more serious and unusual the crime, the more likely the case will be considered for a extension of time pursuant to Welfare and Institutions Code Section 1800.   

If a petition is filed with the court to seek to civilly commit a person to CYA beyond the age of 25, the standard of proof of the first hearing is a probable cause standard.  The Court is required to set a probably cause evidentiary hearing within 10 calender days of the court's probable cause hearing unless the ward waives time.  If the court makes a determination that the person would be physicaly dangerous, the court must order a jury trial and the burden required is proof beyond a reasonable doubt. 

The United States Supreme Court in the case of Kansas v. Crane (2002) 534 U.S. 407 held that the Kansas Sexually Violent Predator Act (SVPA) is not consistent with substantive de process and that to be involuntarily civilly committed a person must, as a result of mental illness or abnormality have serious difficult controling his or her dangerous behavior.  In that case, Michael Crane pled guilty to aggravated sexual battery for two separate crimes occuring on the same day in 1993.  On the first incident, he exposed himself to a tanning salon attendant, which by itself is nothing that would lead one to believe that he had a mentall illness or abnormailty.