Thread The Needle Meaning

(idiomatic) To find harmony or strike a balance between conflicting forces, interests, etc. Normally used to indicate the difficulty of doing so; also, sarcastically, for a failed attempt.

Example: 2010, James C. Foster, Bong Hits 4 Jesus: A Perfect Constitutional Storm in Alaska's Capital, University of Alaska Press (2010), ISBN 9781602230897, page 215:
  Were I writing for the Court, I would seek to thread the needle between acknowledging Principal Morse's authority, on the one hand, while respecting student Frederick's rights, on the other.