The vast majority of Dr. Maris's clients are attorneys seeking expert opinions and testimony about suicide, standard of care issues, medical malpractice, contested life insurance, murder, murder-suicide, worker's compensation and product liability (especially for psychiatric medications). Clients also include organizations, other experts, and the media (see NEWS tab).

Some of the general types of past clients include:

• The United States Department of Justice (See Trentadue, '98;
  Alsept, '01, Parsons, '03, Williams, '11, Bigham, '12, Seastrunk, '13, Senescal, '13, Riopedre, '15, Rice, 19)
   
• Life Insurance Companies (including Western Reserve Life, State Farm, Manufacturers Life, Lincoln, Columbus Life, Transamerica, Equitable, Franklin Life, Unum, Amica, Allstate, New York Metropolitan, Prudential, USF&G, Mutual of Omaha, American General, Founders, United Life, Fidelity, Occidental Life, Federal Insurance).
   
• Airlines (El Batouty & Egypt Air, '04, Cessna, '94, Arrendale, '94).
   
• The U.S. Federal Bureau of Investigation and Police Departments.
   
• Medical Malpractice, Hospitals, Emergency Rooms, VA (See Vets v. Peake, '08).
   
• Home Box Office, British Broadcasting Corporation ("Death By Hanging" '98).
   
• The 110th United States Congress ("The Truth About Veteran's Suicide," '08).
   
• In Re Neurontin (Finkelstein, '05-06, gabapentin).
   
• Product Liability/Drug Cases (including Prozac, Paxil, Lexapro, Wellbutrin, Neurontin, Ambien, et al.).
   
• Murder-Suicides, Murder (See Running, '00, Plude, '02, Peak, '02, Jensen, '03, Theos, '03, Corbin, '06, Sawyer, '07, Sweat, '13).
   
• Jail/Prison Suicide (See Trentadue, '98, Woodruff, '99, Stiles, '13 et al.).
   
• Schools (See Garrido, '97, High, '01).
   
• Celebrity Cases (including Susan Smith, '95, Megan's Law, '95, Della Sutorious (Court TV), '96, Dan Chandler, '97, Phil Hartman (SNL), '98, Pittman, '05, Lawler, 19.
   
• Workers' Compensation.