briar-patch

noun2

1. •
   A dense thicket of thorny plants; ground made impassable by the impenetrable overgrowth of prickly vegetation.

   • Hobbes: I'm sick of going over and through every obstacle on the hill. Calvin: Every obstacle?!? We missed the briar patch, didn't we?! Hobbes: By going down the gully and into the stream, yes. — 1989
2. •
   (figurative) An intellectual or philosophical issue abounding with seemingly unresolvable problems; a theoretical quandary or impasse.

   • Our favorite writers can lead us into ideological brier patches and ethical thickets. — 2016