Justice for ALS Veterans Act of 2021 This bill extends increased dependency and indemnity compensation to the surviving spouse of a veteran who dies from amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) regardless of how long the veteran had such disease prior to death. Under current law, such compensation is paid for a service-connected disability that was rated totally disabling for a continuous period of at least eight years immediately preceding death. For purposes of this bill, a surviving spouse is a person who was married to the veteran for a continuous period of eight years or longer prior to the veteran's death.