The reach of military justice is extensive; it stops at neither serviceman nor service offences. The military Court Martial has jurisdiction over service personnel and reservists alike for both service and civilian offences. It also has jurisdiction over civilians that are subject to service law under the terms of their employment contract and those who fall under military jurisdiction by virtue of their presence on a military base, or their connection with military personnel.
The Forces retain a right to discipline regular serviceman for service offences; that is what one would expect. Every fighting force throughout history has made use of a distinct system of discipline with offences that do not apply to civilians, however, the military Court Martial has jurisdiction over both service and civilian offences. Despite this, the civilian courts do have the primary claim to jurisdiction over civilian offences. Before the Armed Forces Act 2006 it was obligatory for defendants to be tried in the civilian justice system for homicide and serious sexual offences. It was also common for the civilian courts to assume jurisdiction for other serious offences unless they were committed on military property and only involved serviceman. This prohibition was removed in 2006 and now the Court Martial can try serious criminal offences wherever they are committed.
Despite this, it remains common for service personnel to be tried by the civilian courts in circumstances where it might serve the public interest better for them to be dealt with by the Court Martial; service courts have sentencing options that allow for a period of detention followed by a return to service whereas civilian courts do not. Some offences are not compatible with continued service but many others are not fatal to a career in the Forces. The practice of trying them in the civilian courts means that soldiers wishing to return to soldiering are lost to the Army.
Regulars are not the only ones affected. Reservists in their various forms are also caught by military justice. Reservists are broken down into two groups. Firstly, the ‘volunteer reserve forces’, namely the Royal Navy Reserve, the Royal Marines Reserve, the Territorial Army and the Royal Auxiliary Reserve and the Royal Air Force Reserve. These are former regular personnel who have a call-out liability arising from their regular service. Members of the reserve forces become subject to Service law when they are carrying out the following activities:
a] during permanent Service on call-out
b] during home service defence service on call-out
c] when engaged in a full-time Service commitment
d] when undertaking any duty or training
e] when serving on the permanent staff of a reserve force
A reservist undertaking any of these services will be subject to service law during the whole period of that service whether they are travelling, working, resting or off duty. The only exception is d] above where such a person will be subject to Service law while they are with their reserve force only. In addition, members of the reserve force may be tried for certain offences under Part X of the Reserve Forces Act 1996 even when they are not subject to Service law.
Some civilians are also subject to service jurisdiction. The case of Marin v UK  ECHR 40426/98, concerned the seventeen year old son of a corporal serving in Germany. He was charged with the murder of a German national who had been employed by the British Army. The German authorities waived jurisdiction and Corporal Martin was posted back to the UK and left the Army in 1994. Despite the fact that his father had returned to the UK and was no longer serving, the Attorney General consented to Martin being tried by Court Martial and was he convicted of murder. He appealed that conviction to the Court-Martial Appeal Court and Lord Bingham commented that
‘It would in our view have been preferable if this young appellant, whose subjection to military law was purely vicarious and involuntary, had been tried here with all the procedural safeguards which procedure in the ordinary courts afford. We cannot, however, stigmatise these proceedings as abuse’.
Jurisdiction is not confined to civilian dependents. Those who work in some capacity in connection with the Services, for example in the NAAFI, are also captured. Any civilian who visits a person stationed overseas who is subject to Service law or discipline is also automatically subject to the jurisdiction. Civilians can be dealt with summarily by a Service Civilian Court. They do have the right to elect to be tried in the Court Martial if the offence is serious enough.
Despite the observations of the Court in Marin, there is no right for either civilians subject to military justice, or service personnel to elect trial before the civilian courts. There is therefore an inherent disadvantage to those who fall within the military jurisdiction.