I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear that this happened.
Due process requires notice and an opportunity to be heard. A person who is served with notice of a lawsuit, has participated in the lawsuit, and receives a trial has received notice and an opportunity to be heard. That satisfies due process. There is unfortunately nothing in the law that requires a judge to continue a case when a person fails to appear in court on the trial date that they've been told about (and many judges will not continue a case at the last minute). He is allowed to enter a ruling against the person who isn't there. The reason he entered judgment against the defendant is that a person who presents no testimony cannot prove his case. If there had been other witnesses, that may have been different. But in a landlord/tenant dispute where the tenant isn't there, the only thing the judge can do is decide the case based on the landlord's evidence.
There are a couple of arguments that could work here. The lawyer could say "I made a huge mistake and this is all my fault and please do not hold my client responsible for the fact that I failed him", which sometimes helps if he told you that it was OK to skip the trial. Or if there was a genuine emergency that prevented you from attending the court date. Something that arose at the last minute, could not have been anticipated, and made it impossible for you to attend. That could involve things like: you were in the hospital due to the accident, you were overseas and your flight home was cancelled unexpectedly, your car broke down on the way to court - whatever happened that made it impossible to get to court. If you have documentation of an emergency, that makes it much more likely that the judge would reopen the case.
And if the judge doesn't agree to reopen the case because this was something that you were aware of in time to make arrangements to appear, there could be a malpractice claim against the lawyer who did not seek to continue the case at the very first second he found out the defendant was unavailable. Judges don't like to continue a case at the trial, and it's not all that surprising, honestly, that he ruled against the defendant here. That's very common.
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