The Downey case has led to calls for soldiers involved in killings during the Troubles to be exempt from legal action.
The paratroopers involved in the Bloody Sunday shootings are some of the most prominent cases in this category.
A criminal investigation is currently under way into the killing of 14 unarmed civilians by the Army at a civil rights march in Londonderry in 1972.
Up to 20 soldiers still face being formally questioned by police for alleged murder, attempted murder or criminal injury during the notorious incident.
Several Tory MPs, including Sir Gerald Howarth, have said the soldiers should now not be held to account.
He and others argue that if people suspected of involvement in paramilitary crimes during the Troubles can be allowed to walk free, the paratroopers involved in Bloody Sunday should not face the courts.
It is understood a letter is to be written to the Prime Minister calling on him to lift the threat of any criminal prosecution against the soldiers.
One Tory MP said: "I'm damned if they should be given an amnesty and former soldiers left hanging there; uncertain over whether they might face prosecution."
General Sir Richard Dannatt, a former head of the Army, said it would now be "an outrage" if a prosecution were mounted against the Bloody Sunday troops.
He said: "If a double line has been drawn under this for one set of people, then of course a double line should be drawn under this for the British soldiers."
It emerged last week that just 20 out of a possible 1,000 witnesses have come forward to give evidence in the ongoing PSNI investigation which is expected to cover much of the same ground as the Saville Inquiry into the shootings. In 2010, Lord Saville was critical of the Army, finding that soldiers fired the first shot without issuing a warning and that the victims were unarmed.
David Cameron then issued an apology over the killings, saying they were "unjustified and unjustifiable".