Weigh In Meaning

(intransitive, idiomatic) To bring in one's weight, metaphorically speaking, to bear on an issue; frequently construed with on or with.

Example:   Two days before the fight, the boxers weigh in with reporters watching.
  His trailer weighed in lighter than it should have. He might have a leak.
  They had to weigh him in at the loading dock.
  They weighed every third truck in to check for overweight violations.
  He weighs in at upwards of 250 pounds.
  Everyone wanted to weigh in on what kind of car he should buy.
  Everyone spoke freely, until the boss weighed in.
1990, Bryan Burrough and John Helyar, Barbarians at the Gate: The Fall of RJR Nabisco, HarperCollins (2003), ISBN 978-0-06-053635-0, page 322:
  Having more or less approved Drexel [Burnham Lambert]'s selection earlier, he [Peter Cohen, CEO of Shearson] now weighed in with what seemed a halfhearted endorsement of [Thomas] Strauss's [CEO of Salomon Brothers] stance.
Mike Myatt, 8 Tips For Leading Those Who Don’t Want to Follow, Forbes On-line Blogs, Jan. 7 2013, [1]:
  It is absolutely essential to understand other’s motivations prior to weighing in.