According to Shouse California Law Group, folding knives such as box cutters, pocket knives and utility knives are legal to carry in California. A kitchen chef knife or ice pick are categories of knives that are lawful to possess when used normally, but any automatic knife that is determined to be a switchblade is illegal.
Knives that are definitely illegal to carry or conceal in California are switchblades, ballistic knives, cane swords and belt knives, notes Shouse California Group. In general, knife laws in California can be complex, and the average citizen may inadvertently get in trouble for carrying a knife. For example, Penal Code 21310 allows citizens to openly wear a dagger or dirk knife as long as it is inside a sheath. However, concealing these knives is illegal. There are instances where a legal knife can turn into an illegal one. If a person carries a pocket knife that locks into position, that pocket knife falls into the open carry only category.
When a person is arrested in California for carrying or concealing an illegal knife, it up to the prosecutor to prove that the person knew about the knife and that he knew the knife was illegal.