We need a Foolproof Mechanism for Presidential Pardon

Many hailed the recent Supreme Court ruling on the case against the granting of Presidential pardon to former Parliamentarian Duminda Silva who had been convicted for the murder of former Presidential Advisor Bharatha Lakshman Premachandra on October 8, 2011, calling it a landmark judgement. However, their stand on the mater does not seem to be so different than the decision by former President Gotabaya Rajapaksa to grant the pardon to Silva. Both were politically driven. 
The irony of the decision by former President Rajapaksa was that at the time of the murder, both Silva and Premachandra were working closely with him, one as a monitoring MP for the Defence Ministry to which Gotabaya Rajapaksa was the Secretary, and the other as the Advisor to former President Mahinda Rajapaksa on trade union affairs. However, the family of Premachandra distanced themselves from the government alleging that the government of the day was siding with Silva during the investigations.

The Supreme Court ruling on the decision by former President Gotabaya Rajapaksa to grant pardon to Silva was based on technicalities and not on politics or other reasons that prompted the former President in granting clemency. In fact the significance of the judgement would have been far reaching and deterrent on future unethical clemencies, had the prosecution challenged the motive of the former President.  
Why a Head of State should grant pardon to a person convicted by a court of law in the first place is the most important question one has to pose. It could be acceptable, if the convict is languishing in prison for not being affordable to appeal against the verdict of a lower court, or if there is a general perception that there has been a miscarriage of justice as a result of political or personal vendetta by the Executive. 
There were no protests when the former Army Commander, Sarath Fonseka and former Chief Justice Dr. Shirani Bandaranayake were exonerated by former President Maithripala Sirisena, since the miscarriage of justice was clear and the whole country knew that they were victims of Presidential highhandedness. Even Dallas Alahapperuma, a bigwig of the Mahinda Rajapaksa government hailed the decision by President Sirisena to promote Fonseka to the rank of Field Martial. 
However, almost all recent amnesties granted by Presidents to the convicts of high profile cases have been controversial and all of them had been politically motivated and highly unfair by the victims of the relevant cases.  
The pardoning of Mary Juliet Monica Fernando, the wife of a former Minister who was sentenced to death for a double murder in 2005 by former President Mahinda Rajapaksa in March 2009 was the first best example for undermining the role of the judiciary by way of Presidential clemency, in the recent past. In May 2019, former President Maithripala Sirisena similarly pardoned Secretary General of the Bodu Bala Sena, Venerable Galagoda Aththe Gnanasara Thera who was serving a six-year prison sentence for Contempt of Court. The second controversial pardon by former President Sirisena was granted on 9 November 2019 to Don Shramantha Jude Anthony Jayamaha, who was sentenced to death in the Royal Park Murder case.  Later former President Sirisena had said that an investigation has revealed that some individual had taken money to ensure that a Presidential pardon was granted to Jayamaha.
On 26 March 2020, former President Gotabaya Rajapaksa granted a Presidential pardon to former Lance Corporal Sunil Ratnayake, a prisoner on death row for the murder of eight innocent persons in Mirusuvil in 2000. Then, Duminda Silva was released on June 24, along with some others who were also pardoned by the former President.

All these Presidential actions were controversial and clear to be unethical. Former President Gotabaya Rajapaksa not only pardoned convicted criminals but also appointed a commission to overturn a whole lot of court rulings, in the guise of rectifying political victimization. Yet, public opinion prevented it from happening. 
Overturning judicial decisions by the Executive must be carried out on strong legal, as well as ethical grounds, without sending wrong messages to the criminals. It seems to be that the current mechanism can be abused by the Executive to reverse court rulings and release criminals. Hence, the Parliament must take action to introduce a strong foolproof mechanism in this regard.