Complex sentence: The expression "the powers that be" however does not contain a subjunctive: it is a Biblical quotation from Romans 13:1 where it translates a present participle, using the archaic alternative indicative form "be" for "are".
Split into simpler sentences: The expression "the powers that be" does not contain a subjunctive, however. It is a Biblical quotation from Romans 13:1 where it translates a present participle using the archaic alternative indicative form "be" for "are".