From Colorado and Washington state to California and Hawaii, police are being sued by people who want their marijuana back after prosecutors chose not to charge them or they were acquitted.
In some cases, the one-time suspects are asking for hundreds of thousands of dollars to replace dead plants.
Concerns over liability have prompted some agencies to either forgo rounding-up the plants altogether or to improvise by collecting a few samples and photographing the rest to use as evidence for criminal charges.
"None of us really are sure what we're supposed to do, and so you err on the side of caution," said Mitch Barker, executive director of the Washington Association of Sheriffs and Police Chiefs.
The change comes as the notion of marijuana as medicine clashes with police seizure procedure that was developed in an era when pot was a scourge that needed to be wiped out.
"Law enforcement is going to have to think more carefully about what their procedures are and how those procedures might need to change in light of changes in the law," said Sam Kamin, a University of Denver law professor.