- Why no interview w/Trump? From Vol II, Page 13 of the Mueller Report:
“We also sought a voluntary interview with the President. After more discussion, the President declined to be interviewed. During the course of our discussions, the President did agree to answer written questions on certain Russia-related topics, and he provided us with answers. He did not similarly agree to provide written answers to questions on obstruction topics or questions on events during the transition. Ultimately, while we believed that we had the authority and legal justification to issue a grand jury subpoena to obtain the President’s testimony, we chose not to do so. We made that decision in view of the substantial delay that such an investigative step would likely produce at a late stage in our investigation. We also assessed that based on the significant body of evidence we had already obtained of the President’s actions and his public and private statements describing or explaining those actions, we had sufficient evidence to understand relevant events and to make certain assessments without the President’s testimony. The Office’s decision-making process on this issue is described in more detail in Appendix C, infra, in a note that precedes the President’s written responses.”
You’re not getting a more complete answer than that. The better area of focus, imho, in this respect is Trump’s written answers. That has been underreported and his statements are contradicted by the facts.
- What role for OLC memo? From Mueller Report, Vol II, Pg 1-3:
We first describe the considerations that guided our obstruction-of-justice investigation, and then provide an overview of this Volume: First, a traditional prosecution or declination decision entails a binary determination to initiate or decline a prosecution, but we determined not to make a traditional prosecutorial judgment. The Office of Legal Counsel (OLC) has issued an opinion finding that “the indictment or criminal prosecution of a sitting President would impermissibly undermine the capacity of the executive branch to perform its constitutionally assigned functions” in violation of "the constitutional separation of powers."1 Given the role of the Special Counsel as an attorney in the Department of Justice and the framework of the Special Counsel regulations, see 28 U.S.C. § 515; 28 C.F.R. § 600.7(a), this Office accepted OLC’s legal conclusion for the purpose of exercising prosecutorial jurisdiction. And apart from OLC’s constitutional view, we recognized that a federal criminal accusation against a sitting President would place burdens on the President’s capacity to govern and potentially preempt constitutional processes for addressing presidential misconduct.2
Second, while the OLC opinion concludes that a sitting President may not be prosecuted, it recognizes that a criminal investigation during the President’s term is permissible.3 The OLC opinion also recognizes that a President does not have immunity after he leaves office.4 And if individuals other than the President committed an obstruction offense, they may be prosecuted at this time. 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."
Followed by this kicker which has been more frequently cited:
Fourth, if we had confidence after a thorough investigation of the facts that the President clearly did not commit obstruction of justice, we would so state. Based on the facts and the applicable legal standards, however, we are unable to reach that judgment. The evidence we obtained about the President’s actions and intent presents difficult issues that prevent us from conclusively determining that no criminal conduct occurred. Accordingly, while this report does not conclude that the President committed a crime, it also does not exonerate him.
There is a much lengthier discussion of the OLC memo in Vol II. I just pulled the portion from the summary.
On this OLC memo issue, the better approach, imho, is to translate this into English: 1. Trump met the elements to be charged for obstruction. 2. If Trump were not POTUS, he would be charged. 3. The only thing that held Mueller back from actually making a charging recommendation of Trump was his status as POTUS and the OLC memo’s interpretation of the POTUS’ immunities. 4. Mueller would agree that Trump could be charged based on this report when he leaves office (which is also something that he wrote in the report).