(CNN) An attempt from Treasury Secretary Steven Mnuchin to block the release of President Donald Trump's taxes would be "inappropriate and probably illegal," according to Mnuchin's predecessor Lawrence Summers.

"The appropriate response of the treasury secretary is very clear: Under a long-standing delegation order, the secretary does not get involved in taxpayer-specific matters and has delegated to the IRS commissioner as follows: 'The Commissioner of Internal Revenue shall be responsible for the administration and enforcement of the Internal Revenue laws,'" Summers, who served under President Bill Clinton, wrote in a Washington Post op-ed published Monday.

Summers, a Harvard professor who also served as an economic adviser to President Barack Obama, said that the delegation is not "readily revocable" and Mnuchin, under law, would have to notify the relevant committees if he plans not to delegate this issue to the IRS chief.

"So for the secretary to seek to decide whether to pass on the President's tax return to Congress would surely be inappropriate and probably illegal," Summers added.

He argued that neither he nor previous Treasury secretaries would have "interfered with the IRS to contravene a nearly century-old statute that had been applied on many previous occasions."

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