Reference for Bava Kamma 224:7

אי הכי כי פתחו ליה נמי מצי א"ל לב"ד הגדול אזילנא אמר רבינא כגון דנקט דיסקא מבית דין הגדול

the party in question was sent for but did not appear. Rab Judah said that Samuel stated that [evidence of] witnesses may be accepted even if the other party is not present. Mar Ukba, however, said: It was explained to me in so many words from Samuel that this is so only where e.g., the case has already been opened [in the Court] and the party in question was sent for but did not appear, whereas if the case has not yet been opened [in the Court] he might plead: 'I prefer to go to the High Court of Law'.<span class="x" onmousemove="('comment',' In the Land of Israel; cf. supra p. 67 and Sanh. 31b. ');">¹²</span>

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