Can a junior police personnel inquire and arrest a senior Army officer?

Answer 1

This answer is specific to the US Military, though it likely applies in most other counties as well, with the names of things modified as appropriate.

I assume you mean an MP (Military Policeman).

The answer is yes. MPs derive their authority ultimately from the Uniform Code of Military Justice, which "outranks" everyone in a "no man is above the law" sense. Any officer, even the CO of the base, can be arrested by an MP if he's violating the UCMJ.

Answer 2

Yes- If they have broken the law. If anyone breaks the law, they can be arrested by anyone, and even could be placed under citizen's arrest.

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Minor point of terminology- In the US Military, MPs do not arrest. They apprehend service members, and persons that are under the authority of their commander. And yes, A PFC Military Police Officer may place a Colonel under apprehension.

Answer 3

It is a complicated matter with Military Officials exempted from multiple jurisdictions of security agencies regardless of any country except for those who do not have any set of laws defined or where the military does not exist.

NO, Police cannot arrest the Military Officer anywhere in the world unless directed so by the Military itself or the Federal Government asking for an arrest. Even in those cases there is a methodology involved. Uniformed officials after they have recognized themselves to the agency (Police, FBI, CIA) cannot be arrested at gunpoint (there is no question at all) as all uniformed military officials are members of Federal Government not State or Provincial Governments, indeed it is a serious breach of law pointing a gun onto a uniformed military official as they are entitled to self defense where-ever what-ever the situations or consequences are.

But does that mean they cannot be charged for a crime? NO, they can be but to that even an appropriate method is in place. Police official will request the Officer to Comply and Co-operate with them in petty crimes (If they do not comply without recognizing themselves they are treated as civilians, if they have recognized themselves and still do not comply their identity itself is enough to levy a charge against them as it is military not a private organization where employee will runaway or vanish; he has to report to the command when required, thus police prepares a case against the officer and forwards it to their respective command where a court of inquiry (CI) is put in place to greet him the moment he reports back) and a report is initiated that is not dealt by the civilian authorities (civil courts) but are rather forwarded to their respective Command/Units/Regiment for consideration of awarding a penalty. There the Military Courts called usually Judge Advocate General Branch (JAG) of military decrees a penalty against an officer thus no civilian court can try a military uniformed officer. That is in case of petty crimes. (Officers are not kept behind bars as it is been depicted here but rather they are treated with utmost respect and their respective command is informed about it who assign the task to Military Police to procure the officer back to base with details of charges levied against him)

In cases of National Security or where the Case is of a serious nature then federal government asks the military to exempt a particular individual from Army Act and even then the state agencies cannot take the matters into their hand rather Military Intelligence Coupled with CIA or FBI retrieves the individual and if he does not comply he is taken by force a warrant issued not by the Civilian Court but by the Military Courts based on which he is taken into custody.

Case # 1 The concerned officer is not directly presented to civilian courts but is initially presented to military court which on accounts of National Security or a serious breach of law rather exempts him from Army act to be presented to Civilian Court (the official remain under the legal custody of military and JAG Branch representatives are present there in the hearings) if the officer is proved to be guilty the military courts then decree a penalty against him that is usually a court-martial from the military and military imprisonment after which the individual has to face the civilian court again who decree a penalty onto the officer of its own. (i.e if individual on killing another citizen has been confined to military imprisonment for 10 years after which he is released the civilian court decrees a penalty of 15 years then the officer serves another 5 years in prison accounting his military imprisonment of 10 years as penalty is federal not stratified to subjects of federal government i.e Military, Judiciary etc.)

Case # 2 is fairly simple in which if required by the civilian courts for a heinous crime of a civilian nature military Court-Martial the officer after which he is not under the domain of Military law (Armed Forces Act.) rather he is a civilian and faces a criminal penalty of civilian in nature.