Any items consider non-tariff barriers to protect the U.S. industries hindering free movement of the goods ?

Question

What items are justified for importation restrictions by the U.S.?

Answer 1

Typically USA erects barriers to 'punish' countries that it feels are 'not playing fair' or in retaliation for barriers or quota's imposed by those countries

Examples have included (in the past) :-
1) Refusal to recognise US I.P. / Patents / Copyrights or 'passing off' of fake goods or a refusal to pay Royalties
2) Imposing artificial limitations (eg. insisting the product is translated into some specific language 'only' and then opening every shipment and inspecting every individual item to ensure compliance)
3) Giving favourable or better treatment to similar goods from other 'preferred' sources
4) Actively opposing or hindering US foreign policy.

However when it comes down to it the USA neither seeks or needs (or wants) any 'justification' for it's actions ("He who holds the biggest stick calls the tune" :-) )