Justice Rohinton F Nariman has passed the following directions, sitting in a division bench along with Justice S. Ravindra Bhat,

From Para 4,

4. We have also noted that the political parties offer no explanation as to why candidates with pending criminal cases are selected as candidates in the first place. We therefore issue the following directions in exercise of our constitutional powers under Articles 129 and 142 of the Constitution of India:
1) It shall be mandatory for political parties [at the Central and State election level] to upload on their website detailed information regarding individuals with pending criminal cases (including the nature of the offences, and relevant particulars such as whether charges have been framed, the concerned Court, the case number etc.) who have been selected as candidates, along with the reasons for such selection, as also as to why other individuals without criminal antecedents could not be selected as candidates.
2) The reasons as to selection shall be with reference to the qualifications, achievements and merit of the candidate concerned, and not mere “winnability” at the polls.
3) This information shall also be published in:
(a) One local vernacular newspaper and one national newspaper;
(b) On the official social media platforms of the political party, including Facebook & Twitter.
4) These details shall be published within 48 hours of the selection of the candidate or not less than two weeks before the first date for filing of nominations, whichever is earlier.
5) The political party concerned shall then submit a report of compliance with these directions with the Election Commission within 72 hours of the selection of the said candidate.
6) If a political party fails to submit such compliance report with the Election Commission, the Election Commission shall bring such non-compliance by the political party concerned to the notice of the Supreme Court as being in contempt of this Court’s orders/directions.

Citations: [2020 SCC OnLine SC 178]

Other Source links: https://indiankanoon.org/doc/178919210/ or https://www.scconline.com/blog/post/2020/02/13/sc-directs-political-parties-to-publish-criminal-antecedents-of-candidates-give-reasons-for-their-selection/ or https://www.indianemployees.com/judgments/details/rambabu-singh-thakur-versus-sunil-arora-ors

The original Judgment is here.