While sharing a case can be in the best interest of the client there are cautions about making sure you document the relationship. Any time that a Law Firm shares a case with another attorney or refers a case out to another firm, the law firm continues to have exposure for this case. Numerous courts have allowed plaintiff attorneys when pursuing attorney malpractice claims to include all of the attorneys and law firms that have touched a case.
It is important to document with the client the referral with a written agreement that spells out the referral or case sharing understanding. Even if the attorney is not taking a fee for the referral, it is good practice to document and have the client sign any referral to another attorney. If there is no fee involved should document that you are not representing your client in this matter nor have any involvement and have the client sign. You should consult your local bar for the appropriate forms and wording for your jurisdiction.
If you are case sharing or referring cases to other attorneys at a very minimum should make sure and require the firm that is being referred to has malpractice coverage with the limits and deductible that you are comfortable with given the matter being referred.
At a very minimum, a copy of the declarations page showing limits, deductible and prior acts dates should be obtained annually. Better practice is to require the firm that the case is being shared with or referred to, to have a certificate of insurance issued by their insurance agent showing the referring law firm as a certificate holder. The advantage of being a certificate holder is that if the coverage is cancelled during the policy term, the certificate holder should be notified of the coverage termination.