I was listening to a video interview between WSJ and Berkeley law professor John Yoo, about Trump Jr having meeting Russians during his father's presidential campaign. Yoo's opinion was that Trump Jr.'s receiving info from Russian was stupid but not a crime.
His argument was that if Americans were prohibited from giving out info to a campaign, it is more likely a violation to his freedom of speech. When the anchor pressed that what if the informant was an Russian, Yoo's response was like (not sure if I heard him accurately enough though):
"That's harder question when it comes to Russian. the logic of applying to Russians would make it legal all the rough and tumble politics we are having in opposite researches in our own politics with Americans"
I've been struggling to understand his response. What "opposite researches" did he refer to? How that comment helps defend his positions?
The original video can be found here. (The cited text is at 03:36).