The case for free trade is not absolute. There are many reasons, theoretical and practical, where an exception to the general rule of free trade may be desirable. Reasons of national defense, of terms of trade, of national welfare, can all be justifiably given for tariffs. As I and others have discussed elsewhere, these exceptions have high hurdles to clear and rely on some rather strong assumptions, but they remain, at least in theory, justifiable.
But it is important to note with these different justifications is they are all mutually exclusive. The national defense justification is a tariff high enough to prevent competition into the domestic industry. The terms of trade argument, on the other hand, is a sufficiently low tariff designed to generate welfare gains and force other countries to lower their prices. In other words, one tariff is designed to decrease imports and the other to increase imports. These are, obviously, at cross purposes.
Even if these justifications are intellectually impeccable, they remain tactically useless for a simple reason: when scarcityism admits multiple justifications, any number of rent-seeking firms can exploit these various justifications for personal gains. In other words, multiple conflicting justifications can be given by various firms, and all hope of improving national welfare goes out the window; the more exceptions carved out, the more rent-seeking individuals and firms will seek to exploit them. As rent-seeking increases, more and more resources are devoted away from satisfying consumer wants and toward rent-seeking.
The presumption of liberty, that is a tendency to allow free trade vs controlled trade, remains strong even if it is, in theory, the option that has lower welfare because of the potential of rent-seekers to exploit ambiguity in a national policy to promote welfare.