When reviewing a CCMA commissioner's decision on a condonation application, the test is whether the discretion was exercised judicially - i.e., whether it was exercised capriciously, upon a wrong principle, in a biased manner, or for insubstantial reasons with no regard to the principles applicable to condonation applications. Commissioners enjoy a wide discretion in condonation matters and reviewing courts should be cautious when interfering with such rulings. A commissioner's decision will not be set aside on review if the commissioner applied the correct legal principles (such as those in Grootboom v NPA), considered all relevant factors, and reached a decision that a reasonable decision-maker could reach on the evidence. Poor prospects of success in the main dispute constitute a formidable obstacle to condonation, particularly where the opposing party has provided documentary evidence substantiating their defense.