One opinion (which is almost certainly universal),
Regardless of whether the lawyer is representing a civil client or a criminal client, the lawyer’s ethical obligations remain the same. Where a client informs counsel of his intent to commit perjury, a lawyer’s first duty is to attempt to dissuade the client from committing perjury. In doing so, the lawyer should advise the client that if the client insists on committing the proposed perjury then the lawyer will be forced to move to withdraw from representation. The lawyer should further explain that he may be required to disclose the specific reason for withdrawal if required to do so by the court. If the client continues to insist that they will provide false testimony, the lawyer should move to withdraw from representation.
When a lawyer has actual knowledge that a client has committed perjury or submitted false evidence, the lawyer’s first duty is to remonstrate with the client in an effort to convince the client to voluntarily correct the perjured testimony or false evidence. If the client refuses to do so, the lawyer has an ethical obligation to disclose the perjured testimony and/or submission of false evidence to the court.