It happened at a hog farm near me. It took police a long time to get the individuals off the premises.
As I understand it, the legislation will deter people from coming onto the property. Once activists gain entry to the property and occupy it, they do not up and leave just because police are on the scene. The law needs to deter people from breaking onto the property, to prevent the birds from coming under stress, to ensure their welfare and to protect biosecurity.