modern rabbinic rulings

Awareness of the differences between a contemporary, novel application of an ancient ruling and a modern ruling is important for understanding how the system works.

Also, the word "modern" should probably be avoided. In my experience, Catholics often and Jews sometimes mean since ~70 AD by modern (Jews are more likely to mean ~500 AD than ~70 AD), others mean different things, such as since WWII, or within the past few decades, or since 1563.

Further confusion is added when someone has one meaning in mind and pegs it incorrectly to an event or other outside thing they use to describe their use of "modern", e.g. someone who said "Modern Judaism, meaning Judaism that doesn't take "eye for an eye literally, is fairly progressive," might mistakenly think that before fifty years ago, it was taken literally, and intend to mean "within the past fifty years" by "modern".

The best first step to understand the timeline is to learn what insiders think and how they consider rabbinic status across gaps of centuries and so forth. Though I lack any knowledge of scholarship, I am guessing the popular current internal evaluation does much more stratifying into eras with fairly clean chronological breaks than evidence shows is warranted.

Upvotes and internets galore to whoever can think of a word that is more confusing to use and more worthy of tabooing than "modern" when discussing the history of Judaism. "Traditional" and "authentic" are more prejudicial, but they are obviously so, and hence less liable to cause confusion.