President Emmerson Mnangagwa's decision to assign his deputy Constanino Chiwenga the Defence portfolio has been described as a violation of the Constitution, which prohibits a vice-president from holding any other public office.
Mnangagwa last week appointed Chiwenga, the former Zimbabwe Defence Forces commander and Kembo Mohadi as the new vice presidents.
He went on to assign Chiwenga the Defence and War Veterans portfolio previously given to Mohadi while the Zipra veteran was assigned the national healing and reconciliation department.
Former prime minister Morgan Tsvangirai's advisor Alex Magaisa said Mnangagwa had entangled himself in another potential legal mess after he was forced to change his initial Cabinet, which violated the Constitution.
"While he is entitled to assign the administration of a ministry to his vice-president, section 215 of the Constitution specifically compels him to 'appoint a minister to be responsible for the defence forces,'" Magaisa wrote on his popular blog yesterday.
"The problem is that a vice-president cannot, at the same time, be appointed as a minister as that would violate section 103, which prohibits a vice-president from holding any other public office."
He said Section 215 of the Constitution was specific that the president "must appoint" a Defence minister.
"It is not, therefore, enough for President Mnangagwa to assign Vice-President Chiwenga the role of administering the ministry of Defence because that does not constitute an appointment as required under section 215," Magaisa wrote.
"This means legally, there is currently no minister of Defence as required under section 215 of the Constitution, which is a constitutional violation.
"To cure this, the president must appoint a separate minister of Defence.
"Since section 225 makes the same requirement in respect of the intelligence services, the same minister would be responsible for Defence and security.
"He could, if he so wishes, assign Vice-President Chiwenga to supervise and oversee that ministry.
"If this is not corrected, civil society, the opposition or individuals can challenge the president and government through the courts in order to correct this legal misstep."
He added: "In this regard, it is important to understand that unlike other ministers, the position of minister of Defence is constitutionally defined and has a specific mandate."
Harare-based constitutional lawyer Chris Mhike said although section 99 of the Constitution permits the president to assign ministerial duties to his deputies, the Defence ministry was an exception.
He said Mnangagwa's decision to move the civil service to his office was also a violation of the Constitution.
"The consignment of the civil service to the Office of the President and Cabinet (OPC), and the assignment of ministry of Defence stewardship to VP Chiwenga are both highly controversial, and could reasonably be legally challenged," he said.
"Section 201 of the Constitution of Zimbabwe makes it peremptory for the president to appoint a minister who should be responsible for the civil service."
"Neither the president nor the OPC could be deemed to be "a minister."
He added: "Similarly, section 215 of the Constitution absolutely requires the president to appoint a minister, not a VP, to be responsible for the defence forces.
"There are many ministries, departments and portfolios that are not specifically mentioned in the Constitution, for example the national peace and reconciliation Portfolio, the ICTs and Cyber Security ministry or the Governmental Scholarships portfolio.
"The OPC and the VPs could be responsible for those without any dispute; but the civil service ministry and Defence ministry are certainly problematic as they are particularly mentioned in sections 201 and 215 of the Constitution.
"If the president, the OPC and the VPs cannot be ministers (as was suggested by the Constitutional Court in the 2015 NCA case), then the assignment of the duties and statutes under review could well be a violation of the Constitution."
However, constitutional law expert Lovemore Madhuku differed with the two lawyers, saying according to section 99 of the Constitution, it was lawful for Chiwenga to administer the Defence portfolio even if it was "politically unwise".
"The law says the vice-president can be assigned the administration of any ministry, department or an Act of Parliament," he said.
"So there is nothing unlawful with regards to that. But it is politically unwise."
But Madhuku agreed Mnangagwa had blundered by transferring the Civil Service Commission to his office.
"The law is very clear; the president must appoint a minister responsible for the civil service," he said.
"The word 'must' is not optional, but instructive at law. So this transfer is illegal.
"It is a continuation of the illegalities we are seeing in this administration being perpetrated by so-called lawyers.
"At first they appoint nine non-constituency ministers, more than those stipulated by law. They had to reverse that after being exposed.
"Here again they have moved the civil service to the Office of the President and Cabinet when the law is clear that there must be a minister responsible for that.
"It shows that when it comes to constitutionalism, nothing has changed, in fact it is now worse."
Trade unionist Raymond Majongwe said the decision to remove the civil service from the Labour ministry was a violation of the International Labour Organisation convention on the harmonisation of labour laws for the both state and private sector workers.