One thing that is evident to observers of the BDS movement is how thoroughly it is shot through with anti-Semitism. One sees this in ways ranging from allegations that Jews engineered the financial crisis to folks threatening to make Jews' "life hell". And one corollary to that is that institutions enmeshed in the BDS movement have extreme difficulty in crafting any sort of robust policy against anti-Semitism, as to do so would create sharp dissonance with their own avowed politics and priorities. So it was that the UCU -- a prime player in the British BDS campaign -- simply decided to abandon any definition of anti-Semitism at all.
As the American focus of this debate shifts to the Presbyterian Church (USA), one sees a similar pattern emerge. Jewish organizations had already issued complaints that the PCUSA had been deliberately excluding the mainstream Jewish community from deliberations about issues of concern to the Jewish community, instead inviting handpicked representatives from the marginal fringe who would eagerly provide cover to the PCUSA's pre-existing political priors. Meanwhile, as Will Spotts documents, despite its claims to the contrary the PCUSA has been rather consistent in evading any sort of reckoning with potential anti-Semitism -- rejecting internal reports that acknowledge to a problem within their church and demanding instead that any accounts of anti-Semitism be phrased so broadly that they could never firmly be pinned on anything the PCUSA actually does. The prime criteria for what is anti-Semitism, to groups like the PCUSA, is that it can under no circumstances encompass anything that the PCUSA actually does. That, of course, is not how someone who cares about anti-Semitism operates -- that's how someone who cares about ticking the "I'm not anti-Semitic" box off their mental checklist operates.