पृच्छ्यं न पृच्छति अपृच्छ्यं पृच्छति पृष्ट्वा वा विसृजति शिक्षयति स्मारयति पूर्वं ददाति वा इति मध्यममस्मै साहसदण्डं कुर्यात् ॥ कZ_०४.९.१४ ॥
pṛcchyaṃ na pṛcchati apṛcchyaṃ pṛcchati pṛṣṭvā vā visṛjati śikṣayati smārayati pūrvaṃ dadāti vā iti madhyamamasmai sāhasadaṇḍaṃ kuryāt
If a judge fails to ask what ought to be asked, asks what ought not to be asked, dismisses a party after questioning, coaches or prompts a party, reminds him what to say, or gives a prior advantage, he shall incur the middle-grade sāhasa fine.
Selective questioning, irrelevant probing, dismissing after extracting info, coaching/prompts, and granting one side a head start.