One change could make a difference to the availability of transplantable organs in the US: make donation upon death opt-out vs opt-in on drivers' licenses.

There are arguments on both sides of opt-out ("presumed consent"), but even the cons argue more about ethics and lawsuits -- re dead people who clearly no longer need the organs -- than that there'd be more organs available to the living who might.

pro: https://sparq.stanford.edu/solutions/opt-out-policies-increa...

con: http://www.hopkinsmedicine.org/news/media/releases/presumed_...