Politicians who engaged in "whataboutery" when comparing the Kenmure Street and George Square policing responses should "know better", according to an advisory group.
Documents to go before the Scottish Police Authority (SPA) meeting later today outline the difference between the two events in Glasgow, the first in relation to Border Force operations and the second to do with Rangers fans' celebrations.
A letter from John Scott QC, of the independent advisory group, updates the board about discussions over the policing of assembly and protest in a pandemic where he draws the conclusion there was no bias from the force in either incident.
He said: "Members of the public have expressed a range of views on the apparent tolerance of gatherings in Glasgow, contrary to coronavirus regulations.
"Some have suggested that neither event should have been allowed to develop into a large gathering.
"That is to ignore the right of peaceful assembly which, especially outdoors, should be given considerable weight, even in a pandemic.
"Some have compared the two events (many have mentioned earlier events as well in inevitable albeit often incomplete comparison) and suggested that Rangers supporters were treated differently than the Kenmure Street protesters.
"They are right but really only at a point when public order considerations required action to prevent serious injury and damage to property.
"In fact, serious injury was suffered by police officers and others on May 15.
"That alone should be sufficient to distinguish the two events and explain the policing approach, despite attempts by some to indulge in 'whataboutery', including some politicians, who should know better."
The letter goes on to say the approach to handle such incidents should not be determined by public support or abhorrence for a particular group or cause.
On May 13, a crowd of protesters surrounded a Border Force van on Glasgow's Kenmure Street which had two men detained inside, preventing it from leaving.
After a stand-off lasting several hours, with the crowd chanting "leave our neighbours, let them go", Police Scotland officers decided to release the detained men on public safety grounds, with three arrests made.
Thousands of Rangers supporters defied Covid-19 warnings against large gatherings and massed in Glasgow city centre on May 15 after their side's title win.
Five police officers were injured amid the disorder and 28 arrests were made at the time.
One off-duty police officer is among those fined for breaching coronavirus rules after he was spotted among the crowds at George Square.
Scott added in his letter: "Some political and media portrayal of events in Glasgow this month has used the differences in policing approaches to the different events to suggest bias on the part of police Scotland.
"Our work confirms us in our view that bias played no part in operational decisions.
"Public confidence and police legitimacy can nonetheless be impacted by such portrayals."
Iain Livingstone, chief constable of Police Scotland, discussed the two events in his letter to the board.
He thanked officers for their work on the "extremely challenging" day of Rangers fans' celebrations, while he said the Kenmure Street protest developed quickly, which led to them deciding to release the men in the interest of public safety.
