Lawrence Lessig, who heads the Safra Center and hosted the event,
started by defining institutional corruption as:
A situation where influences within an economy of influence tend to
weaken the effectiveness of an institution, especially by weakening
public trust of the institution.
This is an academic definition. What's important to take from it is
(1) the fact that institutional corruption is a situation rather
than an act (and it is hard to deal with IC situations in the usual
criminal-like enforcement mechanisms of a government ethics
program); (2) that in institutions such as governments there is an
"economy of influence," that is, running for office requires funding
(campaign, party, and PAC contributions), and those who provide the
funds generally get influence disproportionate from others by doing
so; and (3) that even when the influence is legal, it weakens public
trust, and this makes government, and its democratic processes, less
effective.