Article 29 of the Vienna Convention protects diplomats from arrest and detention and grants them immunity from civil or criminal prosecution.
President Muhammadu Buhari's surprise nomination on Thursday of his immediate past service chiefs as non-career ambassadors may have been to shield them from prosecution by the International Criminal Court (ICC) for atrocities and rights abuses committed by the Nigerian military under their watch.
This is the view of some Nigerian lawyers who spoke with Premium Times on the development.
There have been calls since their retirement last week for the prosecution of especially Mr Buratai who led the Nigerian Army for about five and a half years.
But Thursday evening, a statement by presidential spokesperson, Femi Adesina, said the president had forwarded the names of the former service chiefs to the Senate for confirmation as non-career ambassadors.
They include former Chief of Defence Staff, Gabriel Olonisakin; former Chief of Army Staff, Tukur Buratai; former Chief of Air Staff, Ibok Ibas; and former Chief of Naval Staff, Abubakar Sadique.
Their nominations come a week after they resigned from service and their replacements were inaugurated.
Their confirmation as ambassadors will confer on them diplomatic immunity.
Article 29 of the Vienna Convention protects diplomats from arrest and grants them immunity against civil and criminal prosecution.
PREMIUM TIMES had reported some of the human rights abuses carried out under the watch of the retired Army Chief, Mr Buratai. His tenure of over five years was characterised by the extrajudicial killings of hundreds of Nigerians by soldiers.
These ranged from the killing of hundreds of Shiites in Zaria, the shooting of innocent civilians who were protesting at the Lekki Toll Gate to the extrajudicial killings in Oyigbo, an Igbo settlement in Rivers State.
The soldiers and officers involved in the killings were never prosecuted or punished, an indication the atrocities were committed with the approval of the army leadership.
Calls for prosecution
Mr Buratai, a lieutenant-general, was appointed by President Buhari in July 2015.
Nigeria's main opposition party, the Peoples Democratic Party (PDP), just last week asked the ICC, INTERPOL and other world bodies to institute investigations into Mr Buratai's tenure as army chief.
The PDP, in a statement by its spokesperson, Kola Ologbondiyan, alleged that Mr Buratai and the other former military chiefs committed crimes against humanity.
Also, the Concerned Nigerians Group said it had instituted a case against the former COAS at the ICC over what it described as human rights violations and crimes against humanity by the army during his tenure.
In a letter last Thursday by its Convener, Deji Adeyanju, the group asked the ICC to investigate, arrest and prosecute Mr Buratai to serve as a deterrent to others.
The ICC Chief Prosecutor Fatou Bensouda had said last year that the court had received sufficient information to investigate Mr Buratai and his colleagues for alleged war crimes in the war against the Boko Haram insurgents in the Nigeria's North-east.
But Mr Buratai had dismissed the statement, saying he was not afraid of being charged for war crimes.
Going by the Vienna Convention on diplomatic relations, Mr Buratai will enjoy diplomatic immunity while he remains an ambassador.
The convention grants privileges to member nations like Nigeria that enable their diplomats to perform their duties without the fear of arrest or prosecution.
Article 29 of the convention states:
"Diplomats must not be liable to any form of arrest or detention. They are immune from civil or criminal prosecution, though the sending country may waive this right under Article 32."
Other articles which protect diplomats include Article 22 which protects diplomatic premises such as embassies. It states that such embassies must not be entered by host countries except with permission.
"The host country must never search the premises, nor seize its documents or property. Article 30 extends this provision to the private residence of the diplomats," another provision of the law reads.
Also, Article 24 establishes that the archives and documents of a diplomatic mission are inviolable. The receiving country shall not seize or open such documents.
It further states that a diplomatic bag must not be opened even on suspicion.
A Senior Advocate of Nigeria, Afam Osigwe, expressing disappointment at the nomination of the former service chiefs as diplomats.
He said the government should have waited for the outcome of their investigation before their nomination.
Mr Osigwe said the manner of the nomination suggests it was done solely for the sake of conferring immunity on the former service chiefs.
"I would have thought the government should have been circumspect in nominating any person who has charges pending against him or her before the ICC for crimes against humanity.
"I thought it would have been better for any responsible government to have waited for the outcome of such investigation before appointing such persons.
"The manner the five former service chiefs are being nominated for ambassadorial posting makes it look as if the whole idea is to give them diplomatic immunity from prosecution and that should worry all of us about the image of the country and what message we are sending across to the entire world.
"But then, the appointment is still subject to confirmation by the Senate. Going by what we have seen from the Senate, I do not expect to see the Senate reject any of those nominations.
"But then again, the countries to which these individuals may be posted reserve the right to accept their letters of credence, accepting them as Ambassadors of their countries.
"We watch and see but I do not think this goes well for Nigeria, for human rights and also accountability in governance," he said.
Another lawyer, Inibehe Effiong, described the appointment as an immoral attempt to convey diplomatic immunity on them so that they can evade the prosecutorial jurisdiction of the ICC.
He urged the Senate to reject the nominations.
"President Buhari has by this ignoble appointments reminded Nigerians that he is deaf to their cries and blind to their suffering. No leader in this country in my lifetime has exceeded Buhari's parochialism and provocative indifference to public opinion.
"These former service chiefs were supposed to be fired long ago, but because we have a president who has an unbreakable covenant with failure, they were retained in defiance of the resolutions of the National Assembly and the opinion of most Nigerians.
"After removing them belatedly, this president has now rewarded them for superintending over the mass murder(s) of citizens by the Armed Forces and non-state actors such as Boko Haram and the so-called bandits. In other words, Buhari is telling them 'thank you for keeping to my covenant with failure'.
"The appointments appears to be an immoral attempt to convey diplomatic immunity on them so that they can evade the prosecutorial jurisdiction of the International Criminal Court.
"If the Senate has an iota of self-respect and decency, they should reject these abominable nominations. If they are confirmed, it will reinforce the belief that the current National Assembly is working against the interest of the citizens," Mr Effiong said.