Brazil's Arbitration Law (Law No. 9.307/1996, as amended) establishes core duties for arbitrators: impartiality, independence, competence, diligence, and discretion (Art. 13, §6). Arbitrators must disclose circumstances likely to raise justifiable doubts about their impartiality or independence before and during proceedings (Art. 14, §1). These align with judge disqualification rules in the Code of Civil Procedure (Arts. 144-145).Self-disclosure relies on arbitrator honesty, creating risks if conflicts—professional ties, prior relationships, or undisclosed convictions—are omitted. Non-disclosure can violate public policy principles (Art. 21, §2), leading to award annulment if proven to breach impartiality (Art. 32). Awards procured by corruption, extortion, or prevarication are null (Art. 32, VI). Recent Superior Court of Justice rulings clarify that mere non-disclosure does not automatically annul awards; actual bias must be shown, but undisclosed criminal convictions or ties have led to challenges.Corruption risks are heightened in Brazil post-Operation Car Wash, exposing tainted contracts and potential arbitrator influence. Though rare, allegations of arbitrator bias via undisclosed links persist. Best practices demand parties conduct independent due diligence beyond disclosures. The 2024 Brazilian Arbitration Committee (CBAr) Guidelines impose a "duty of due diligence" on parties: search publicly available information (professional history, prior arbitrations, relationships, criminal records) before confirming arbitrators. Parties may pose targeted questions to candidates. This complements the arbitrator's disclosure duty and parties' "duty of curiosity" for accessible facts.Thorough background checks—reviewing CVs, institutional rosters, court records, media, and conflict databases—mitigate risks, prevent late challenges (waived if not raised promptly, Art. 20), and safeguard award enforceability. Failing this exposes parties to annulment actions, delays, and costs, undermining arbitration's efficiency and integrity under Brazilian law.