Can an attorney or law firm hire their client(s). My attorney says they can't hire clients.

It is accurate to state that attorneys do not hire clients. Clients hire attorneys.

An attorney may not form a relationship with a client that may place the attorney in an adverse relationship with the client. Given this, many attorneys do not want to hire clients to do any work for them. For example, say you are an accountant and you hire the attorney to help you in a car accident. The attorney might not want to hire you as an accountant to avoid any problems should he later on develop a dispute with you say over a bill or something along those lines.

It is not illegal for a law firm to hire a client to work for them. However, it may be against the policy of the law firm, and for good reasons. There is a potential for conflict of interest where you would have two different relationships to the firm. Suppose you want to fire them from the case? Does this fire you from your job? Suppose there is a job problem? Will this interfere with the case? Will your possible promotion depend on how the case turns out? Most lawyers would find it unwise to hire a client on a pending matter. It is legal to refuse to hire you for any reason, or no reason at all, except for certain things specifically barred by law, such as racial or gender-based discrimination.