https://www.businessinsider.com/why-...o-his-report-5
""Mueller's report lays out three main reasons why prosecutors didn't indict Trump or suggest he should be charged:
They adhered to the OLC's 1973 decision that a sitting president cannot be indicted.
They believed that if their report suggested Trump could face federal charges without actually bringing them, it would not be fair because there would be no trial, and he wouldn't have an opportunity to clear himself.
Mueller did not consider filing a sealed indictment against Trump out of fear that it would be leaked and significantly impede his ability to govern.""
"""The OLC opinion also recognizes that a President does not have immunity after he leaves office," they added. "Given those considerations, the facts known to us, and the strong public interest in safeguarding the integrity of the criminal justice system, we conducted a thorough factual investigation in order to preserve the evidence when memories were fresh and documentary materials were available."
That wording leaves open the possibility that Trump could be charged with obstruction of justice once he leaves office.""