Attorneys refer and have cases referred to them all the time.  Attorney to attorney referrals are the lifeblood of the law industry, and referral fees are not uncommon.  The law of attorney fees is a body unto itself, and legal malpractice involving referred cases is not uncommon.  Here is a Third Department Case Whalen v. DeGraff which illustrates when the referring attorney may become liable for the acts of the referred attorney.