In the US stuttering is a disability under the ADA, Americans with Disabilities Act, which was first enacted in 1990 and then amended in 2011 to add additional protection for people with disabilities. The ADA recognizes disability if it significantly limits daily acts of living, communication being one. Here is a link to better understand why stuttering is a protected class as per the ADA. It’s long but you can skim it for the parts that might help for explain the how and why of the American with Disabilities Act. https://www.govinfo.gov/content/pkg/CFR-2011-title29-vol4/xml/CFR-2011-title29-vol4-part1630.xml