The ADA applied to the state and the state police and city/county/state jails. The ADA do NOT apply to the federal government. Section 501 of the Rehabilitation Act of 1973 apply to the federal government. If a deaf person in federal jail (is there something wrong to be a deaf inmate??) want a terp, he/she can ask for one under Section 504 of the Rehabilitation Act of 1973. The SSA and IRS offer sign language interpreters if a member of the public request for it. BTW, the whole federal judicial branch (district courts to Supreme Court) claimed they are not under the ADA or Section 501. But they do under the foreign language interpreters guidelines. stupid but true.
see ADA Home Page - ada.gov - Information and Technical Assistance on the Americans with Disabilities Act