Legacy Items in the strictest sense are any magical item build before the founding of the T.C.A. which is the country in which Night School takes place. More practically though it referse only to those items which are actually illegal to own, use or construct due to much of the old magic being un regulated and unrestrained and consiquently often times excessively powerful and frequently dangerous.
Given the monumental nature of trying to round up and destroy all legacy in the TCA the authorities have taken a more relaxed approach and generally don't go kicking down people's doors looking for legacy except for truely dangerous items. They will however not ignore it if one comes to light.
Mainly they are asking for co-operation from the citizens in rounding up and destorying legacy items and are attempting to educate children as to the dangers of said items.
Many legacy items are still out their either owned by collectors, hidden as family treasures (they want Grand Ma's wand? Never!) and most often simply because the owner are not aware the item is either magical or on the banned list.