I can not speak for GumWar, but I am on the SCB and have written around six decision letters this semester. The language we are required to use is a "On the basis of all evidence received, the Student Conduct Board finds that the Dean of Students (has proved/has not proved) by a preponderance of evidence the allegations above." So it's definitely not likelihood, but preponderance of evidence that more likely than not the violation occurred. This policy can be traced back to the Dear Colleague Letter under the Obama administration in respect to Title IX cases, however even though the policy was reversed in 2017 by Devos, it still is the standard procedure for general misconduct and academic integrity violations.

Students that come before the board are rarely arguing that the violation did not occur whatsoever but rather that there is a mitigating circumstance that should be considered when assessing sanctions, or that can explain why a violation occurred. Most professors are not quick to file with the DoS, and only do so after collecting evidence that they believe proves a violation, but that does not guarantee that the DoS will pursue sanctions.

If a student is honest and forthcoming about their innocence throughout the process, and has evidence that proves their innocence against evidence brought by a professor it rarely comes to the SCB. And if it does, every SCB panel I have been a part of where the student argues their innocence with evidence or mitigating circumstances, we have found them not in violation or have significantly reduced the sanctions.