The Independent Police Conduct Authority (IPCA) has rejected a complaint from the CTV families about the police investigation in to the building's collapse.
Police decided in 2017 not to lay 115 charges of manslaughter against the building's designer David Harding, and his employer Alan Reay.
The decision followed advice from the Solicitor General that a prosecution would not succeed.
Last year, the families complained to the IPCA.
In September this year, the authority said it had no jurisdiction over decisions made by Crown Law.
Families spokesperson Maan Alkaisi said despite this, the battle for justice would continue.
"We have never seen a worse design than this building, there's definitely a major departure [from the expected standard]. Even the IPCA admitted that there are numerous design deficiencies and a major departure."
Alec Cvetanov, who lost his wife in the collapse, said the findings of the Royal Commission, which found dozens of errors in the building's design, must be acted on.
"To the government, please don't allow those absurdities to grow up into perversions."
He and the other families asked the prime minister to intervene and appoint one or two retired judges to independently review the police decision not to lay charges.