Modeling an edict on a biblical verse, even though there is independent logic for the edict: Ketuvot 50a
Whether creating a "Fence" is a good or bad thing: Shabbat 153b
Not creating an institution which will cause a poor reputation for practices which pre-date it: Gittin 5b
Not creating an edict prohibiting a Biblical practice, so as to teach that the practice is Biblical: Succah 43b
Not creating an edict which entirely eliminates a biblical practice: Ketuvot 52b
Not creating an edict prohibiting a practice if the Courts are the ones responsible for that act [, since the court is reliable]: Succah 43b
Not creating an edict prohibiting practice X, where it will degrade popular respect for Mitzvah Y: Succah 43b
Not creating an edict which could cause unnecessary impurification of pure items: Niddah 3b, 5b
Not creating edict X, where it will lead people to keep away from Mitzvah Y for fear of violating X: Menachot 51b, 52a; Niddah 3b
Not creating an edict to prohibit practice X lest people do practice Y, because the circumstances of X and Y are dissimilar: Beitzah 3a
Not creating an edict which could lead to loss of money [פסידא]: Ketuvot 60a
Making an Edict where people will not [be able to] listen to it: Yevamot 112b
Making an Edict where people will possibly not keep it correctly: Gittin 3a
Abolishing an Edict where it could cause error: Rosh HaShanah 31b
Suspending a practice because it appears Christian: Taanit 27b
The "Fences" of false time-limits limit the practice of certain Mitzvot: Berachot 2a
Creating a Prohibition which will only be for certain hours, insted of an entire day: Pesachim 2b
Not making an institution for rare cases [milta d'lo schechicha lo gazru beih rabbanan מילתא דלא שכיחא לא גזרו ביה רבנן]: Eruvin 62a, 63b-64a, 67b; Succah 23a; Beitzah 2b; Nedarim 44a; Gittin 5a [2x], 17a-b, 18a; Kiddushin 28b; Bava Metzia 46b; Bechorot 3a; Temurah 18a; Niddah 7b
Not making an Edict/Institution to protect an earlier Edict/Institution [Gezeirah l'Gezeirah גזירה לגזירה]: Eruvin 4b, 99a-b; Succah 6b; Beitzah 3a; Yevamot 109a; Bava Metzia 5b
Prohibiting via multiple layers of decrees, "don't do x lest you do y, lest you then do z," because it's all one decree [chada gezeirah חדא גזירה]: Beitzah 3a
The Rabbis make edicts expanding a person's rights for financial matters, but not where that could affect prohibitions: Bava Metzia 27b
Creating an edict for a population that has avadim, because avadim tend to be careless: Beitzah 14a-b
Tailoring an enactment to avoid risks from people's carelessness: Beitzah 15b
Not making an edict prohibiting some action out of a concern for a certain result, because there would be no end to such decrees [ein ladavar sof]: Bava Metzia 60a
Making Blanket Edicts - Lo Plug לא פלוג
Making edicts which apply equal logic to all applicable cases: Niddah 4b
Not making an edict which will require hair-splitting distinctions for the qualifications of cases: Megillah 18b; Gittin 14a
Not going too far with a prohibitve edict [Mafriz al haMidot]: Niddah 4b
Baking bread with designs on Pesach, which could become Leaven if designing takes too long; some were able to make it faster than others: Pesachim 37a
Not differentiating between different states of marriage, when allowing/forbidding a female minor to refuse an arranged marriage: Yevamot 107a
Not differentiating between handling/redemption of Maaser Sheni whether the walls of Jerusalem are standing or not: Bava Metzia 53b
In rulings on verification needed for Bills of Divorce outside Israel: Gittin 4a [2x]
In who may deliver a Bill of Divorce: Gittin 5a [2x]
The clause in a ketubah stating that a woman's sons will inherit her ketubah applies whether or not the woman's father gave her a dowry: Ketuvot 52b
The clause in a ketubah stating that a woman's sons will inherit her ketubah does not apply to daughters, even in a case where the father only left behind daughters, even though logically it should apply in such a case: Ketuvot 52b
Institutions are Outlined to Parallel Biblical Laws [Ki'Eyn De'Orayta Tikkun כעין דאורייתא תקון]