conditional constructions - When I put 'is' instead of 'be' in: "If she be found guilty"

If she be found guilty… (YBM #8)

I got a curiosity what difference there is when I put ‘is’ instead of ‘be.’ The dictionary says ‘is’ is used in spoken language. Is that all? Is there no semantic difference at all?

Answer

This is a remnant of the old subjunctive, which is no longer used in Standard English conditionals outside of historicizing contexts. You may freely substitute either a simple present or should be—except, of course, in quotations:

If this be treason, make the most of it! —Patrick Henry

Fee, fi, fo, fum
I smell the blood of an Englishman
Be he alive or be he dead
I’ll grind his bones to make my bread —Old tale

If music be the food of love, play on. —Twelfth Night