The Client Files series consists of all documents associated with Green and/or Mitchell's professional activities on behalf of their clients. The material in this series dates from 1812 to 1855, with the bulk dating from 1824 to 1855. Both Green's and Mitchell's professional activities are well-represented in these Client Files, though somewhat more of this series appears to pertain to Mitchell's work. A few of the Client Files relate to Mitchell's practice during his years in Charleston.

Legal documents comprise the bulk of this series; examples of these include court filings, replications, subpoenas, depositions, interrogatories, affidavits, agreements, mortgages, insurance contracts, and assignments. Among these documents are originals, certified copies, unofficial copies, polished drafts, and rough drafts. Most of the client cases concern financial matters, such as disputes over debts or settlements of estates, therefore, financial records also comprise a sizable portion of this series. Examples of these financial records include estate inventories, debt and revenue account listings, drafts, receipts, and summaries of attorney costs.

While most of the Client Files have only a few documents in them, several files are quite extensive. By far the most extensive Client File is that of Samuel Storm who was a longtime client of Green and, after his death, Mitchell. Storm was involved in a number of lawsuits related to his business dealings, and his file reflects this. The Client Files of Alexander Brown and Manning Koster are also substantive with respect to legal matters arising from their business dealings.

The estate work performed by Green and/or Mitchell is represented in the Client Files of Henry Oldring, Michael Megrath, Eliza Evertson, and John Geyer, among others. Aside from estate work, other legal matters which Green and Mitchell undertook can be found in the Koon file (slander against the moral reputation of Esther Koon), the Stremmel file (privateering award), and the Farrington file (military service benefits). Mitchell's activities on behalf of the Episcopal Church, primarily in Charleston where he held a position as Treasurer, are represented in the Protestant Episcopal Missionary Society file.

Subsequent to Green's death, Mitchell acted as attorney for members of the Green family in at least two matters that are well represented in these Client Files. One involves the intra-family dispute between Mitchell and various Green family members with Andrew Haswell Green over Andrew's questionable financial dealings involving the family farm in Worcester. The second matter concerns the dispute of Timothy R. Green's estate with Green's longtime client, Samuel Storm.

Client Files bearing the names of John or Clarence Mitchell include legal matters Mitchell pursued for himself or his son.

The Client Files are arranged in alphabetical order by client name. No distinction is made in the arrangement between clients of Green and of Mitchell; many clients were supported by both attorneys, particularly those longtime clients like Storm and Megrath. Within each Client File, only a broad arrangement is in place: correspondence is found first, followed by legal documents of various types, then followed by financial and other documents. Within each of these broad categories, no arrangement has been established. The Green, Megrath, and Storm Client Files consist of multiple folders; the dates on the folders reflect the contents of the overall Client File, not the specific folder in hand.

This series consists of all correspondence which is personal in nature or that could not be linked to a client relationship during processing. The material in this series dates from 1808 to 1848, with the bulk dating from 1822 to 1839. The series includes some correspondence received and sent by Mitchell, but the bulk of the correspondence consists of letters received by Green. Most correspondents in this series are represented by fewer than five letters, but Green family correspondence is more numerous, especially that from Timothy R.'s uncle, William E. Green, and his cousin, William N. Green. The largest number of pieces of correspondence were received by Green from "cousin" Lucinda (Lucy) Larned who wrote to him regarding both personal and personal business matters. Correspondence "sent" by Green or Mitchell consists of draft notes or retained copies. Correspondence between individuals other than Timothy R. and John Mitchell is also in this series, as is correspondence involving unidentified parties.

Green's correspondence is foldered separately from that of Mitchell. Correspondence received by Green or Mitchell is foldered separately from that sent. The material is filed in alphabetical order by correspondent, then chronologically within correspondent. Some correspondence is signed only with a first name or initial, so that is used to determine alphabetic order. Correspondence from one writer who signed her letters variously as "M.," "Mary," or "M.E.D." is filed together under "D." Some correspondence includes notes from two writers on the same sheet of paper; filing order was determined based on the name of the first correspondent. Correspondence to Green or Mitchell from unidentifiable (e.g., unsigned or illegible) correspondents is filed after the last identifiable writer. Correspondence to Timothy R. from individuals with surnames of Green or Larned is foldered separately from other correspondents.

Correspondence involving Green family members (other than Timothy R.) is foldered separately. Correspondence involving individuals other than Mitchell, Green, or other Green family members is foldered separately. Correspondence involving unidentifiable correspondents is foldered separately.

This series consists of agreements and receipts among Green Family members, as well as notes on Green Family genealogy. Documents related to the generation immediately preceding that of Timothy R. are particularly well-represented. Much of the material consists of original documents, but copies of agreements are also included. The original material in this series dates from 1805 to 1837; the dates of the copied agreements also fall within this range.

Materials, other than correspondence, that could not be linked to a specific client relationship are in the Other Documents series. The material in this series dates from 1827 to 1861, with much of it undated. The series includes legal papers and financial records associated in all likelihood with the work of Green or Mitchell, though that role is not readily identifiable. Public notices of property sales (some with annotations made presumably by Mitchell) are found in this series. Three booklets of corporate Articles of Association, genealogical notes, schematics of building lots, a list of papers left by Mitchell with William Rice in South Carolina, legal research notes, two business cards, a newspaper clipping, and fragmentary reference notes are arranged in this order in a Research Notes folder. Document wrappers are foldered separately.