Marvin concentrates his practice in estate planning and administration, business, tax and elder law. He assists clients by creating estate planning documents such as wills, trusts, health care proxies, and durable powers of attorney, in order to distribute their property and appoint fiduciaries to oversee estate and trust administration. The estate plans range from simple wills to complex tax-minimization trusts and other devices.

Additionally, Marvin advises clients in the creation of business entities such as corporations, limited liability companies, and partnerships, and prepares contracts, agreements, and other documents. He provides counsel on the purchase and sale of businesses, succession planning issues, and asset protection strategies.