The Foyle MLA said that the Devenny family should not have had to wait 50 years after an inquiry was conducted to access the information it holds.
The Metropolitan Police has extended the closure on the Devenny files until 2022.
Said Mr Eastwood: “The Devenny family have been waiting for almost 50 years for access to an inquiry report into Samuel’s death following an attack by RUC officers.
“And even now, there’s no guarantee that further obstacles won’t be placed in their path as the date on which the report could be disclosed approaches.
“The way this family has been treated is grossly insensitive and unfair but sadly it’s a common theme as the apparatus of the British State continues to resist disclosure of documents which could provide a degree of truth for victims.
“The families of all victims deserve access to truth, justice and accountability. Institutional attempts to deny or frustrate that should come to an end.
“No further barriers should face the Devenny family in their campaign for truth.
“These documents should be disclosed at the earliest possible opportunity,” added the SDLP leader.