Authorities are able to do this by utilizing civil forfeiture laws. Laws vary in each state, some states require the individual whose property is being confiscated to have committed a crime, but many do not.
The civil forfeiture laws are especially terrible in Pennsylvania. In one recent case the Philadelphia Police were able to seize the dream home of a hard-working family because their twenty-two-year-old son had been arrested for selling $40 worth of heroin. The cops claimed that the young man had been selling heroin out of the house. The parents asserted that they had no idea their son was dealing drugs out of the family's house, but that is irrelevant to civil forfeiture cases in Pennsylvania. The cops took the house anyway.