> Hér skal og sækja hvert mál sem í fjóðungsdómi utan það er nefndar

eru fernar tylftir í fimmtardóm, þá skal sækjandi nefna sex menn úr
dómi en verjandi aðra sex. En ef hann vill eigi úr nefna þá skal
sækjandi nefna þá úr sem hina sem verjandi átti. En ef sækjandi nefnir
eigi úr þá er ónýtt málið því að þrennar tylftir skulu um dæma.

It went over my head too, I'm afraid, so all I can do is quote Magnus
Magnusson and Hermann Pálsson:

"Court procedure shall be the same as in the Quarter Courts, except
that plaintiff and defendent shall each have the right to challenge
six of the four dozen judges appointed to the Fifth Court; and if the
defendent does not wish to excercise this right, the plaintiff must
challenge six more. But if the plaintiff fails to do so, his case
shall be dismissed, for the judges may not number more than three dozen."

According to their entertainingly understated footnote, "Njal's Saga
gives a broadly accurate but rather confusing version of the
provisions governing the Fifth Court."

> og skal þá velja til þess er vitrastir eru og best að sér.

"and there shall be chosen for this those who are wisest and of the
best character" (or something like that). MM & HP: "wisest and most
sensible". See CV 'at' IV.5. - right hand column [
http://lexicon.ff.cuni.cz/png/oi_cleasbyvigfusson/b0027.png ].

> lofa eða í lög leiða

MM & HP change the order in their translation, I'm guessing for
stylistic reasons, to put the heavier element last: "over the making
of law or the granting of exceptions".

> þá skulu þeir ryðja lögréttu til og skal ráða afl með þeim.

MM & HP: "the issue shall be decided by a majority vote."

> En ef sá er nokkur fyrir utan lögréttu að eigi nái inn að ganga eða

þykist borinn vera máli þá skal hann verja lýriti svo að heyri í
lögréttu og hefir hann þá ónýtt fyrir þeim öll lof þeirra og allt það
er þeir mæltu til lögskila og varði lýriti."

MM & HP, paraphrasing in places: "But if anyone is prevented from
entering the court or thinks himself coerced, he may veto the
proceedings within hearing of the court, and with that veto invalidate
any descisions the court may have made."

More literally: "If there is anyone outside of the Court of
Legislature who doesn't succeed in going in and thinks himself borne
down [wrongfully] in the case (see Zoega 'bera' (5)), then he shall
forbid/prevent [it] with a veto in such a way that they hear in the
court (i.e. in their hearing), and he will have made void then all
their licenses/permissions [if the granting of such was what they were
ruling on] and everything [else] which they spoke/pronounced
concerning legal business (i.e. all the proceedings of the court),
forbidden/prevented (i.e. nullified) [it] by [his] veto."

I wondered if 'varði' might have been a typo for 'varið' (neuter past
participle / supine), but Konráð Gíslason and Eiríkur Jónsson also
have 'varði' [
http://dp.rastko.net/projects/projectID438a3f4017f9f/projectID438a3f4017f9f_TEI.txt
], so I don't know...

lög-skil, n.pl. [
http://lexicon.ff.cuni.cz/png/oi_cleasbyvigfusson/b0406.png ].

Note the indefinite use of the pronoun 'sá', which Faarlund mentions
in his Old Norse Syntax, and which we've met a few times already in
this saga.

Alan wrote: "After that Skafti Þórodd's-son exclaimed `what in god´s
name has the crazy old man been rattling on about' but nevertheless
pronounced the Fifth-Court into law [...]"

Maybe he didn't want to admit that he hadn't understood a word of it,
and risk having to listen to it all over again ;-)