Casillas Law Group

About the Firm

Casillas Law Group is a corporate law boutique, specializing in corporate and business matters for companies ranging in size from startup companies to large publicly traded corporations in the United States and overseas. Casillas Law Group was founded by Mark Casillas in 2003.

Mark Casillas has decades of experience advising on high technology business and finance matters, including company formation, founders shares, securities issuance, equity/debt finance, merger, acquisition, divestiture, restructure, strategic partner, joint venture, stock options, warrants, regulatory, arbitration, litigation, corporate governance, and other matters throughout the USA, Europe, Asia, and Latin America. In addition to high technology, Mark has led engagements in numerous industries, including education, energy (oil, hydro, coal, wind, solar, geothermal, cogeneration, green), banking, venture capital, aviation, sports stadium, music, entertainment, winery, and other industries.

Mark has practiced law with large law firms headquartered in New York and in Silicon Valley, and now he runs Casillas Law Group. Prior to CLG, Mark practiced law at Wilson Sonsini Goodrich & Rosati where he helped run one of Silicon Valley’s largest corporate practices. At WSGR he led teams that advised public and private companies on M&A transactions; financings; offerings of common shares, preferred shares, debt, and convertible securities; strategic partnerships; IPO’s; stock buybacks; licensing agreements; listing (and delisting) proceedings; litigation; arbitration; stock option and executive compensation; employment matters; all ’33 Act and ’34 Act filings; Sarbanes-Oxley; board of directors; and corporate governance. WSGR’s clients included 3,000 high technology startups and 600 publicly traded technology companies. Apple, Google, Twitter, Netscape, and Pixar are among the many clients WSGR led from startup to publicly traded market leaders.

Prior to WSGR, Mark practiced law at LeBoeuf Lamb Greene & MacRae in San Francisco. LeBoeuf was headquartered in New York, one of the world’s leading international law firms. He led transactions throughout the USA, China, Russia, Southeast Asia, Japan, India, Europe, Saudi Arabia, and Latin America, working with that law firm’s offices in New York, Washington DC, London, Paris, Brussels, Moscow, Riyadh, and Almaty. He helped lead the team that opened the firm's office in Beijing.

In addition to high technology and international transactions, Mark continues to do what he’s done for 35 years: advise on a wide variety of business matters in a multitude of industries. He has advised on bond and project financings since 1980. He worked on the SF Giants baseball stadium financing, on the merger/affiliation of two universities, on winery acquisitions and financings, and on a $26.5 million bond financing for a green energy project which was the first of its kind.

Mark serves, and has served, on the Board of Directors of numerous technology companies and businesses, a bank, a university, and non-profit organizations.

Mark received his BA (History) from Loyola Marymount University and his JD from Harvard Law School where he was Managing Editor of the Harvard CR-CL Law Review, the nation’s leading public interest law review. After Harvard, Mark clerked for the Honorable Oliver Seth, Chief Judge of the United States Court of Appeals, Tenth Circuit. Before moving to San Francisco in the 1980s, Mark began his career in corporate and finance law at Breed, Abbott & Morgan, a Wall Street law firm in New York. Mark is a member of the Bar in California and New York. Please contact Mark Casillas with any questions you may have about Casillas Law Group. For more information see