He is allowed to under the trade act... but it has its limitations.
He didn't use the trade act for most though because of the 150 day limitation - instead he's using IEEPA, which was never intended to be used for tariffs, and was intended to be used for Emergencies... Even if the USA was getting screwed on every single trade deal with every single country, it wouldn't be an emergency... At least not the way IEEPA was intended. Theres a very good chance al IEEPA tariffs get thrown out the window - He's enacted some tariffs via other acts, I believe some under the trade act.... I'm betting those stay, until its past the 150 days, in which it'll goto court if he tries to skirt the congress rule... which I'm sure he will. That, or he'll drop the tarrifs on day 149 and re-impose them
My biggest gripe about Trump is he's not a politician, he's a real estate mogul. He doesn't know the proper way to do things, and thats why half his shit ends up in court battles.... Whether what he's doing should be done or not, he's not going about it the proper, legal way - And it ends up being a mockery of the whole seperation of power and 3 parts of government thing.... I'm sure every president thinks his powers being limited by congress / the supreme court are pesky and wish they could bypass it... He's just one of the first to openly do it so much and hope it gets past.