Under California law, "'an attorney is forbidden to do either of two things after severing [the] relationship with a former client. [The attorney] may not do anything which will injuriously affect [the] former client in any matter in which [the attorney] formerly represented [the client] nor may [the attorney] at any time use against [the] former client knowledge or information acquired by virtue of the previous relationship.'" Oasis W. Realty, LLC v. Goldman, 51 Cal. 4th 811, 821 (2011) (quoting Wutchumna Water Co. v. Bailey, 216 Cal. 564, 573-574 (1932)); see also In re McIntosh, No. 13-11774 AJ, 2015 WL 241130 at *5 (Bankr. N.D. Cal. Jan. 16, 2015) (same). Specifically, counsel may not undertake a concurrent or successive representation that has a "substantial relationship" with the prior representation and is adverse to the former client.