The binding legal principles established are: (1) The rule that arbitration proceedings must not be conducted 'inaudita altera parte' does not prohibit all communications or interactions in the absence of a party, but applies where evidence is received, merits are considered, or there is a realistic possibility that a party's rights or interests are adversely affected. (2) For removal of an arbitrator under section 13(2)(a) of the Arbitration Act on grounds of irregularity, there must be actual prejudice or a realistic possibility of prejudice to a party's rights or interests, not merely a procedural defect. (3) The test for reasonable apprehension of bias in arbitration is whether a reasonable, objective and informed person would, on the correct facts as they emerged, reasonably apprehend that the arbitrator has not brought or will not bring an impartial mind to the adjudication. This test must be applied ex post facto with the benefit of hindsight based on what actually occurred. (4) Where an arbitrator acts in good faith to protect the interests of absent parties and makes no rulings or findings that could affect their rights, and was under a bona fide but mistaken impression that the parties were aware of the meeting, this does not constitute grounds for removal on the basis of bias or irregularity.