Are both parties obligated to participate in an unemployment appeal hearing ?

Sometimes, the denial of benefits is not because the employer has challenged it. It could be the intake worker formed an incorrect opinion based on what he or she was informed. Other times, the employer simply may not think it is worth the time, effort and money to attend a hearing to fight the claim. It happens where the employer does not show up. This does not mean you automatically win. You still have to convince the ALJ you meet all the eligibility criteria. Of course, it makes it much easier to do so when there is no direct testimony to refute your testimony. Good luck.