In the more than year and a half Robert Mueller spent compiling his final report on Russian meddling in the 2016 election and possible collusion with President Donald Trump’s campaign, he was required to follow several federal regulations that govern special counsel investigations — from what’s included in the memo to how it’s delivered to the Justice Department.

The report must explain why the special counsel is advising for or against prosecution, according to the regulations. But some of the rules are thin; for instance the rules only stipulate that the special counsel must deliver a confidential report to the U.S. attorney general at the conclusion of the work — not that it must be made public, a point of public debate throughout Mueller’s probe. It is up to the attorney general to decide whether to prosecute and whether to publicly release any of the report.

Read the full federal regulations for a special counsel below:

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