Let there be no doubt: You can bring marijuana to the 2015 U.S. Open at Chambers Bay. However, you can't smoke it.
Marijuana is legal in Washington, meaning that, despite conflicting federal law, local officials have no legal authority to confiscate someone's personal weed stash, even if it comes with them to the golf course. The USGA has chosen not to make a stink about it, telling entrance-gate staffers to let tournament patrons in, even if they're in possession of some weed.
While bringing marijuana to the U.S. Open is completely OK, smoking it isn't. Washington's marijuana laws prohibit people from smoking in a public place, which Chambers Bay is. So that means that, as far as we know, folks are lighting up doobies along the rope line.
And, no, it's not a hemp rope.