Legal think tank, Veritas says government's decision to deploy the country's military to support police in maintaining public order during the January protests was unconstitutional.
The group argues in a statement issued last week that the decision did not get parliamentary consent as required by law hence violates the country's Constitution.
Veritas said that the Constitution requires Parliament to be promptly informed of any such deployment.
"The President 'must cause Parliament to be informed, promptly and in appropriate detail, of the reasons for their deployment and ... the place where they are deployed," said Veritas quoting the Constitution's section 214.
President Emmerson Mnangagwa deployed the army after violent protests broke out in January following the announcement of a 150% increase in the price of fuel. The protests called by the Zimbabwe Congress of Trade Unions (ZCTU) as a stay-away initially turned into an orgy of violent in which police stations were ransacked.
Some 17 people were killed in the melee that followed while scores were left with gunshot wounds that the army attributed to "rogue members" as well as activists who had stolen military fatigue and guns during the mayhem.
At the time of the protests and the deployment, Parliament was in recess. Veritas expressed concern that two weeks after the deployment, Parliament resumed as scheduled on 29th January but even after MDC Mutare Central MP, Innocent Gonese raised a point of Parliamentary privilege on the matter, no ruling was made by the Speaker of Parliament Jacob Mudenda.
"Since the 29th January and to date - despite the fact that both Houses of Parliament have sat on 12 separate occasions - members of Parliament have still not been formally informed by their presiding officers (Mudenda and the President of the Senate Marble Chinomona) that Parliament has received communication from the President on the matter," Veritas said.
However Mnangagwa last week issued a statement through Justice Minister Ziyambi Ziyambi notifying Parliament of his decision to deploy the military.
The legal watchdog concluded that there has been a serious breach of section 214 of the Constitution because the word "promptly" has been ignored and underlined that the Executive has "treated Parliament with disrespect if not contempt."
Mnangagwa last year deployed the military after another bout of protests broke out over delays in announcement of presidential election results. The army reportedly used live ammunition killing six unarmed civilians. The President was forced to set-up a Commission of Inquiry headed by former South African President Kgalema Motlanthe to investigate the killings. Despite denials from military leaders, the Commission found the army culpable for the murders.