I left a job and gave only a day notice, then started new job next day.
The new job I was on for only 3 months, then hurt my knee, and could not work. They then let me go. I can work now, so I filed for unemployment. The unemployment went back to my original employer because of time with second employer. Original employer is contesting, saying that I did not give proper notice when I left. Can an employer use this excuse?
Thank you

There is no law that limits what an employer can use as a reason to contest unemployment. How much weight the state will give to their reason is unknown.