The singer's filed new legal docs in the Eastern District of NY, obtained by TMZ, asking the court to throw out charges for knowingly exposing sexual partners to herpes because ... he says the legislature didn't include herpes in the law because it's "Not An Acute, Bacterial Venereal Disease."

You might recall, federal prosecutors accused Kelly of exposing 2 people to an STD in March 2020, and the charges were tacked on to his already long list of federal charges for allegedly sexually exploiting underage girls and young women.

According to the new docs, however ... Kelly's legal team claims herpes does not fall under the umbrella of STDs -- like syphilis or gonorrhea -- based on how the term has been defined by the New York State Dept. of Health and the World Health Organization.

He points out those orgs classify herpes as a virus, not a bacterial venereal disease -- and therefore, he wants the herpes-related counts dismissed.

As we've reported ... Kelly's also gearing up for his criminal trial in Chicago, and dealing with the recently added allegations that he groomed and molested a 17-year-old male he met at McDonald's.