No, "sheriff's deputies" should not be in uppercase unless it appears at the beginning of a sentence or is part of a proper noun.
Chamber of Deputies of France was created in 1875.
Chamber of Deputies of France ended in 1940.
Chamber of Deputies of Rwanda was created in 2003.
Chamber of Deputies of Luxembourg was created in 1848.
Non-Partisan Deputies was created in 1973.
Board of Deputies of British Jews was created in 1760.
Chamber of Deputies of Mexico was created on 1821-09-28.
Congress of People's Deputies of Russia ended in 1993.
Congress of People's Deputies of Russia was created in 1990.
principles, deputies, and interagency policies
Each estate elected its own deputies to this body?"