Alun Cairns MP has been cleared of breaching the ministerial code following claims he knew about a former aide's role in allegedly sabotaging a rape trial.
Mr Cairns quit his cabinet position as Secretary of State for Wales last month following the claims he lied about his knowledge of Ross England's involvement in the collapse of a rape case.
A Cabinet Office investigation said it was "unlikely" that Alun Cairns would not have been told anything about his former staff member's role in the collapsed trial.
However, the report added, "But all those involved state they had not informed Mr Cairns of Mr England's role, and there is no direct evidence to contradict this.
"On that basis, I do not find that the evidence upholds the allegations of a breach of the ministerial code."
The report by Sir Alex Allan, the Prime Minister's independent adviser stated that Mr Cairns said he knew about the collapse of the trial, but that he did not know the details until they become public.
"Mr Cairns worked closely with his special adviser, who had had conversations with Mr England and who was more likely than not to have known about Mr England's role though I accept that Mr Cairns' special adviser would not necessarily have known the judge's actual remarks," he wrote.
Sir Alex said the issue was whether it was "plausible that Mr Cairns could have been told about the collapse of the trial without inquiring or being told about the reasons, especially given that he knew Mr England was a witness".
"Mr Cairns' asserted that he was not a lawyer and did not then understood the difference between an adjournment, a delay and a collapse. It seems to me that these terms are self-evident."
Mr Cairns stood by his claims he was unaware of the role played by his former staff member, Ross England, in the collapse of a rape trial until after the story broke.
However, he was accused of "brazenly lying" after BBC Wales said it had obtained a leaked email which suggested he had been made aware of the allegations as early as August last year. Mr Cairns said he would "co-operate in full" with an investigation into his actions under the Ministerial Code, adding that he was confident he would be cleared of "any breach or wrong doing".
Mr Cairns told ITV Wales following his resignation he stood aside as Secretary of State so the Cabinet Office could "make a judgement" when he was questioned whether he should stand as a candidate in the general election.
"I hope people will allow due process to continue."
Mr Cairns held his seat in the Vale of Glamorgan with a majority of 3,562.
Mr Cairns was replaced as Welsh Secretary by Simon Hart earlier this week following the Conservatives' election victory on December 12