Beis Din - Authority comes from being agents of Israeli beis din which had semicha - how does that work?

Tur (Choshen Mishpat 1): Today, when there is no ordination, all the judges are unqualified according to the Torah, as it is written, “before them,” [Exodus 21:1] meaning before ’elohim, as written in the pericope, which is to say ordained [judges], and we interpret that to mean “before them and not before laymen,” and we ourselves are laymen [in that sense]. Therefore there are no judges with authority from the Torah except if they act as the agents [of the ordained judges of Palestine].

Prof Radzyner has a very interesting article on the authority of the contemporary beis din [click link]

Abstract: A sugya just a few lines long in the Babylonian Talmud, Gittin 88b, had enormous influence on the development of Jewish law in the area of the authority to pass judgment given to rabbinical courts in our day. According to the simple, commonly accepted understanding of this sugya, the Tannaim ruled that the Torah forbade men who had not received ordination to act as judges, and as a result, the judges in Babylonia were permitted to adjudicate, of necessity, only as agents of the judges of Palestine we act as their agents). The article reexamines these positions. The first part suggests two new ways to understand the essence of the agency of which R. Joseph spoke in the sugya. The second part of the article reexamines the source of the prohibition, to the extent that it exists, against adjudication by laymen