The nation's strongest laws against sprawl are beginning to buckle here in Oregon under pressure from an even stronger, voter-approved law that trumps growth restrictions with property rights. In a collision between two radically different visions of how cities should grow, claims under Oregon's new law are pitting neighbor against neighbor, rattling real estate values, unnerving bankers and spooking politicians. The property-rights law, which was approved overwhelmingly by voters last fall and is known as Measure 37, is on the brink of wrecking Oregon's best-in-the-nation record of reining in sprawl, according to state officials and national planning experts.