The move by the United States Department of Justice (DoJ) to seize assets allegedly linked to 1Malaysia Development Berhad (1MDB) is legally flawed, according to a senior Malaysian-born Australian lawyer.

Quintin Rozario, a prominent litigation lawyer in Brisbane, said by making public statements on Malaysian individuals allegedly to have laundered illicit funds into the US, its Attorney-General Loretta Lynch had herself committed "excesses and breaches of natural justice".

Rozario told Bernama from Brisbane that Lynch overstepped the mark and her authority by concluding that an offence or offences had been committed by Malaysia or its agents.

"She went further by implying that they were guilty of the offence by making assertions without a scintilla of proof or a valid court decision that could back her assertions.

"In order for that to occur, the Malaysian defendants ought to first to have been heard. They were not," he said.

Rozario said it was a legal principle that even the most vile of criminals were deserving of and entitled to the doctrine of natural justice under the constitution.

"The right to be heard and to be afforded an opportunity to present their defence, to challenge the assertions and charges and the evidence against them and for the respondents in this matter to confront their accusers has not yet arisen.

"For the highest legal officer of the land in Loretta Lynch to act in such an arbitrary manner as she has recently is to deny the respondents a fair hearing or any hearing at all. Loretta has become a judge, jury and executioner all in one," he added.

Rozario said the US Attorney-General's action was also clearly against a decision made by the US Supreme Court in 2014 in the case of Daimler vs Baume, in which the apex court ruled that any violation of act committed by residents in the US, their conduct could not be atributed to the government or as in this case, 1MDB.

"Instead the Supreme Court ruled that their activities would only establish specific juridiction in the state they reside in the US," he said.

Lynch, in prepared remarks to announce the legal action on July 20, said among other things that a high-flying Malaysian businessman known as Jho Low had allegedly laundered hundreds of millions of illicit funds into the US, which funded real estate purchases and a lavish personal lifestyle.

"The 2014 US Supreme Court decision is a clear authority that even if Jho Low or others mentioned in the complaint were residents of any state of the US and were agents of 1MDB or the government of Malaysia and that they had committed a violation of any act in their state, their conduct could not be attributed to the government or 1MDB," said Rozario.

The lawyer also spoke of the US record of observing international law which he described as "inconsistent at best and selective and flawed at worst".

He said the US had the economic, political and military might to exercise over those who they could and wished to subdue.

"Loretta Lynch's approach to 1MDB follows a long line of authority of the US using strong arm tactics on smaller states. It does this by appropriating to itself powers to dilute Malaysia's sovereignty and to enforce against it 'legal obligations' usurping that power from the US and Malaysian courts and other arms of their goverment," he added.

Rozario's arguments reinforced Prime Minister Datuk Seri Najib Tun Razak's remark on Thursday that due process needed to be respected and that those named in the DoJ action should have a chance to defend themselves, including in court.