There are currently some policies that are not defined as uncancellable but they should. Any country has to define some policy and laws regarding some ethic issue. Here is a short (not exhaustive!) list of what should be defined as uncancellable, with a debatable proposition for slider positions (some of them are actually already implemented in the game, but not as uncancellable):
position on gay community and rights: forbidden, some tolerance, civil union, marriage, adoption, surrogacy agreement
euthanasia: life above all/no intensive medication/assisted suicide/active euthanasia
death penalty: forbidden/terrorism only/violent crime only/any crime
drugs legalization: strongly sentenced/criminal activity/therapeutic usage allowed/no restriction
prostitution: strongly prosecuted/criminal activity/proxenetism illegal/soliciting illegal/no restriction
organ donation: forbidden/on death/medical allowance/commercial use
birth control: restrictive policy/no governmental intervention/some encouragement/benefits and tax-cut for parents
military service: none/a few months/several months/a year/two years/very long
minimum wage: none/very low/low/medium/comfortable
and some additional possible age-sliders : driving licence age, voting age, majority, length of study (or legal age for quiting school), retirement age
Please feel free to add your comments and thoughts! (some of these points are already part of some mods).