The unions watchdog has concluded its long-running donations investigation into the Australian Workers' Union without recommending any action against officials.
The Registered Organisations Commission informed the AWU of its decision on Thursday night.
Australian Federal Police raids on AWU offices in 2017, initiated by the ROC, sparked controversy and years of legal action after media was tipped off.
The investigation centred on whether donations from the AWU to Labor candidates and GetUp were properly authorised when Bill Shorten led the union.
Mr Shorten insisted all donations made before he entered parliament in 2007 were above board.
The ROC said in a statement its investigation concluded the AWU contravened a section of the commission's legislation on nine occasions by lodging annual loans, grants and donations statements late or not at all.
And the union "did not follow the processes set out in its own rules".
"However, because of the deficient record keeping practices of the AWU, the effluxion of time, and its inability to produce relevant documents, the investigation was unable to attribute any of the specific failures by the national executive or the AWU to any one or more individuals or office holders," the commission said.
"There was insufficient documentary evidence of specific conduct ... to recommend any further regulatory action against any individuals."
The commission said that had the AWU cooperated in August 2017 the matter could have been resolved within two to four weeks.
AWU national secretary Daniel Walton said former Industrial Relations Minister Michaelia Cash now owed the union and the nation an apology.
"The AFP raids launched on our offices in 2017 were one of the most shocking abuses of power by an Australian government in modern history," Mr Walton said in a statement on Friday.
"The donations made by the AWU at the centre of this investigation were never remotely secret, let alone concealed.
"Yet the coalition government's ROC has spent thousands of hours, millions of taxpayer dollars, and the resources of the Australian Federal Police, trying to get mud to stick to the AWU and its former national secretary Bill Shorten - who just happened to be opposition leader at the time. All over a paperwork issue."
