If the lawyer is purchasing the debt for the sole purpose of bringing suit, they may be breaking the law.
http://calbar.ca.gov/state/calbar/ca...9&id=1287#6129 §6129. Buying Claim as Misdemeanor Every attorney who, either directly or indirectly, buys or is interested in buying any evidence of debt or thing in action, with intent to bring suit thereon, is guilty of a misdemeanor. Any violation of the provisions of this section is punishable by imprisonment in the county jail not exceeding six months, or by a fine not exceeding two thousand five hundred dollars ($2,500), or by both. (Origin: Pen. Code §161. Amended by Stats. 1976, ch. 1125.)
More information and court cases on this topic.
http://www.lacba.org/showpage.cfm?pageid=433 The purpose of the statute, as is that of champerty laws in general, is to prevent the officious fomenting of litigation. The outright purchasing by attorneys of claims which perhaps otherwise would never be sued upon obviously would tend to stir up a good deal of litigation if it were permitted; but the transfer by one who owes money to an attorney of a claim which the transferor possesses against a third person may have but insignificant effect in the volume of litigation, and it partakes much less of the officious intermeddling of out-and-out purchase and sale . . . ."
Consistent with the foregoing cases, the proposed conduct in this Inquiry would not violate Section 6129 in the following circumstances: (1) where an attorney does not buy a debt or chose in action, but rather obtains an assignment of an interest in the proceeds of a claim; (2) where the attorney does not obtain the assignment with the intent to bring suit thereon, either as a party to the lawsuit or as the attorney to the party, and (3) where the assignor brings the actions in his or her own name and is represented in the action by an independent attorney.
As for other states, start checking those laws to see if there is a similar statute.