
James Steinseifer, 33, of Makakilo, was being held on $300,000 bail.
Police have said Steinseifer was legally drunk Jan. 7 when his car crossed the center line of Farrington Highway between Waipahu and Kapolei and crashed into an on-coming car.
Nicole Nuuanu-Dudoit, 22, her 24-year-old sister, Carina Nuuanu, and their 1-year-old niece, Laakea Nuuanu, were killed in the accident. Nuuanu-Dudoit's 6-year-old son, Blake, was the only person in their car to survive the crash.
The usual charge in traffic fatalities is negligent homicide, which has a maximum 10-year prison sentence. Prosecutor Peter Carlisle decided upon manslaughter, which carries a 20-year sentence.
"The difference between manslaughter and negligent homicide in the first degree has to do with state of mind," Carlisle said. "And the state of mind that you're looking at is reckless, as opposed to gross negligence, and the use of the vehicle with alcohol involved."

The Navy successfully demonstrated Friday that it could knock down an incoming ballistic missile with another missile during tests at the White Sands Missile Range in New Mexico.
Rear Adm. Rodney Rempt, program executive officer of the Navy's Theater Air Defense in the Pentagon, said in a telephone interview from Washington, D.C., "the significance of today's tests means we can use existing Aegis ships and our already existing missiles, with certain modifications, and use them to intercept incoming missiles."
USS Lake Erie (CG 70) and the USS Port Royal (CG 73), both homeported at Pearl Harbor, will be modified to conduct sea tests, develop warfighting doctrine and tactics and serve as a focal point for the new anti-missile defensive system.
The two Pearl Harbor guided-missile cruisers were chosen because "they are located in areas where we might have to use them," Rempt said.
Kauai's Pacific Missile Range testing facility also will play a vital role in the Navy test program, he added.
"The tests we did today stretched the limits of what we can do at White Sands ... obviously from Kauai we can conduct much more extensive and longer range tests at sea," Rempt said.
Rempt said the White Sands test involved a SM-2 Standard missile, which the Navy has been using for the past 30 years, but which was modified with a state-of-the-art infrared heat-seeking device. The target which was shot down was a version of the Army's surface-to-surface Lance missile.

House Judiciary Chairman Terrance Tom (D, Kaneohe-Kahaluu) said the measure addresses the "legitimate concerns" of couples prohibited from marrying and includes benefits - such as inheritance rights - most often raised in hearings.
Rep. Bob McDermott (R, Aiea-Foster Village) said in opposition that special rights should not be given to people who choose to engage in particular behaviors, "whether it's homosexuality, bisexuality, pedophilia, necrophilia or whatever it is."
But Rep. David Tarnas (D, South Kohala-North Kona), one of 18 who voted in favor with reservations Friday, said the bill did not go far enough to meet equal protection standards.
The bill would take effect only if voters in next year's election ratify a proposed constitutional amendment passed Thursday that would limit marriage to heterosexual couples.
Sens. Avery Chumbley (D, East Maui-North Kauai) and Matt Matsunaga (D, Waialae-Palolo), meanwhile, introduced a proposed amendment giving the state power to reserve marriage for heterosexuals as long as its application "does not deprive any person of civil rights on the basis of sex."
The Senate Judiciary Committee co-chairmen said their proposal addresses both community concerns and a Hawaii Supreme Court ruling which said the state cannot discriminate based upon gender.