Fulton County, Ga., District Attorney Fani Willis (D) penned a scathing letter to House Judiciary Chairman Jim Jordan (R-Ohio) after he asked her to turn over all documents related to her prosecution of former President Trump and 18 others on charges related to election interference.
The nine-page letter at turns accuses Jordan of “offend[ing]” Constitutional principals with “your attempt to interfere with and obstruction this office’s prosecution,” suggests he buy a book on racketeering prosecution at the price offered for non-attorneys and casts her response as voluntary as “settled constitutional law clearly permits me to ignore your unjustified and illegal intrusion.”
“Your attempt to invoke congressional authority to intrude upon and interfere with an active criminal case in Georgia is flagrantly at odds with the Constitution,” Willis wrote in a letter first reported by the Atlanta Journal–Constitution and also obtained by The Hill.
Not an attorney so I can't say. But in the full quote it seems to be a lawerly book so maybe, just like licensed contractors can get discounts on hardware they would use in their trade (like for construction or auto mechanics).