The Amendment Act of 1950 brought the law up to date, led to new regulations in 1952, and enabled a full-time quarantine service, staffed by trained men, to function at all airports and ports of entry. These officers, who form the first line of defence against the introduction of diseases, meet all overseas ships and aircraft; board passenger ships in the stream, examine passengers' luggage, and inspect ships' cargoes and goods arriving by parcel post and mail. Plants growing in post-entry quarantine are also inspected for any signs of disease which might not be evident at the time of their arrival in this country.

Depending on the results of the examination at the port of entry, goods are either allowed free entry, entry under restriction of growing in post-entry quarantine, or fumigation or other treatment; or else they can be refused entry and either reshipped or destroyed. Since 1952, plants and plant products have been divided into three classes: (1) those safe to allow entry to; (2) those too dangerous to allow entry to; and (3) those which are allowed entry under certain conditions.