Mueller Report, vol. I, p. 2: In evaluating whether evidence about collective action of multiple individuals constituted a crime, we applied the framework of conspiracy law, not the concept of "collusion." In so doing, the Office recognized that the word "collud[e]" was used in communications with the Acting Attorney General confirming certain aspects of the investigation's scope and that the term has frequently been invoked in public reporting about the investigation. But collusion is not a specific offense or theory of liability found in the United States Code, nor is it a term of art in federal criminal law. For those reasons, the Office's focus in analyzing questions of joint criminal liability was on conspiracy as defined in federal law.
Mueller Report, vol. I, p. 2: In connection with that analysis, we addressed the factual question whether members of the Trump Campaign "coordinat[ed]" — a term that appears in the appointment order — with Russian election interference activities. Like collusion, "coordination" does not have a settled definition in federal criminal law. We understood coordination to require an agreement — tacit or express — between the Trump Campaign and the Russian government on election interference. That requires more than the two parties taking actions that were informed by or responsive to the other's actions or interests. We applied the term coordination in that sense when stating in the report that the investigation did not establish that the Trump Campaign coordinated with the Russian government in its election interference activities.
Mueller Report, Vol. 1, p. 10: The investigation did not always yield admissible information or testimony, or a complete picture of the activities undertaken by subjects of the investigation. Some individuals invoked their Fifth Amendment right against compelled self-incrimination and were not, in the Office's judgment, appropriate candidates for grants of immunity. The Office limited its pursuit of other witnesses and information-such as information known to attorneys or individuals claiming to be members of the media-in light of internal Department of Justice policies. See, e.g., Justice Manual §§ 9–13.400, 13.410. Some of the information obtained via court process, moreover, was presumptively covered by legal privilege and was screened from investigators by a filter (or "taint") team. Even when individuals testified or agreed to be interviewed, they sometimes provided information that was false or incomplete, leading to some of the false-statements charges described above. And the Office faced practical limits on its ability to access relevant evidence as well-numerous witnesses and subjects lived abroad, and documents were held outside the United States. Further, the Office learned that some of the individuals we interviewed or whose conduct we investigated-including some associated with the Trump Campaign—deleted relevant communications or communicated during the relevant period using applications that feature encryption or that do not provide for long-term retention of data or communications records. In such cases, the Office was not able to corroborate witness statements through comparison to contemporaneous communications or fully question witnesses about statements that appeared inconsistent with other known facts.
