Nagy Britanniában ezt használják.

You instruct (engage) a solicitor, and the solicitor will send you a Client care letter in which he outlines the terms of engagement, including fees.

Client care letters are a vital tool for communicating essential information to your client at the outset of a retainer. The information contained in a client care letter can outline the parameters of the retainer and be used as evidence against complaints of insufficient information or inadequate professional services.
http://www.lawsociety.org.uk/productsandservices/practicenot...

Két rövid leírás az ügyvéd megbízásához vezető lépéseknek és az ügyvéddel szemben támasztott követelményeknek:

6. A solicitor will ask you to sign a client care letter. This letter will state what the firm will do for you, what you can expect, and what they expect from you. Client care letters are pretty standard in the industry. They have complete disclosure regarding the services and costs. By signing the client care letter you have committed to the firm or the solicitor with a legally binding agreement.
www.diylegals.co.uk/find-a-solicitor/

És:
4. When accepting an instruction, law firms must send a client care letter setting out terms and conditions at the beginning of the relationship, outlining costs and timings, who will be in charge of the case and who to approach in the firm regarding complaints. Legal terminology e.g. ‘disbursement’ should be explained clearly.
http://www.takelegaladvice.com/home/why-use-takelegaladvice....

Ez a példa barristertől származik, de a lényege ugyanaz:
http://www.barristersdirect.co.uk/client_care_letter.html