A civil suit before the Arizona Supreme Court challenges whether the state is required to upgrade older roads to meet new safety standards — and the liabilities it faces when it doesn’t.

“It has been the law in Arizona since the 1920s that the state and municipal governments are responsible for keeping the roadways reasonably safe,” Tucson attorney John Leader said.

Leader represents Diana Glazer, a California resident whose husband and 6-year-old daughter died in a crossover car crash on Interstate 10 near Phoenix in 2007. In a crossover crash, a vehicle crosses the center of the road and into oncoming traffic.

In 2012, a Maricopa County Superior Court jury awarded Glazer $7.8 million. Glazer’s attorneys argued the state was negligent in not maintaining modern road safety measures, such as median or lane barricades along the stretch of I-10 where the fatal crash occurred.

The case has the rapt attention of Arizona counties and cities, as many worry that the court’s decision could force them to continually maintain roadways and other infrastructure to meet constantly evolving design and safety standards or face an onslaught of lawsuits.

In the Glazer case, the state has not denied that the fatal accident occurred. It just contests its responsibility and whether damages should be paid.

State law ARS 12-820.03 says neither government is liable for an injury “arising out of a plan or design for construction” of a roadway “if the plan or design is prepared in conformance with generally accepted engineering or design standards in effect at the time” the road was built.

The law, however, requires drivers be given “reasonably adequate warning” of “any unreasonably dangerous hazards,” so they can take suitable precautions.

The state argues that the section of I-10 where the accident occurred met standards in place when it was built in 1967.

The section in question is south of Phoenix near Milepost 171 on the Gila River Indian Reservation. It has two lanes in each direction and a wide, barrier-free median.

The Arizona Department of Transportation did not want to comment about the pending lawsuit, but a spokesman for the agency emailed the Arizona Daily Star a statement on I-10 crossover accidents initially released in April.

“The Arizona Department of Transportation takes seriously all collisions on state highways, including cross-median crashes, which are a small percentage of serious crashes on the Interstate 10 corridor between Phoenix and Tucson,” the statement reads.

The statement also said the state has implemented numerous safety improvements along the I-10 Tucson-to-Phoenix corridor.

Attorneys for the state are challenging an Arizona Court of Appeals ruling that the government should maintain reasonably safe infrastructure, updating and improving it to evolving standards, as conditions and circumstances change.

In this instance, the changing conditions are the many-fold increase in traffic volume and new safety standards intended to prevent crossover accidents.

In court documents attorneys for the state argued: “The court, not the Legislature, added the changed-circumstances exception. If the Legislature had intended to withhold immunity because of changed circumstances, it would have said so.”

In addition, the state argues that the Appeals Court effectively subverted the will of the Legislature by allowing the “changed-circumstance exception.”

In a brief filed in support of the state’s position, 13 Arizona counties argue against the Appeals Court ruling, saying it would effectively impose a crushing financial burden on local governments.

“If left standing, the Court of Appeals’ ‘changed circumstances’ exception … would saddle the counties with legal, financial and operational obligations they cannot possibly fulfill — to continuously evaluate and update every roadway within their jurisdictions or face potential liability for failing to do so,” attorneys for the counties wrote.

The brief notes that Arizona counties have a combined responsibility for nearly 8,000 miles of paved and 11,200 miles of unpaved roads.

The counties acknowledge an obligation to maintain roadways to reasonable safety standards, but they say policymakers and Department of Transportation officials should be free to set their own priorities.

The Arizona League of Cities and Towns also filed a brief in support of the state arguing municipalities face constant changes and could not keep up as conditions change.

“To go back and retroactively upgrade every inch of roadway would be just impossible,” said Ken Strobeck, executive director of the Arizona League of Cities and Towns. “There’s just not enough money in the world to do that.”

Pima County filed its own brief in support of the state’s position, picking up the argument that the Appeals Court has undermined the Legislature and violates the separation of powers doctrine by allowing judges to “second-guess” legislative decisions.

Pima County Supervisor Ally Miller, who represents District 1, has been an advocate of fixing the region’s dilapidated roadways since running for office two years ago.

While she was unable to speak about the Glazer lawsuit specifically because the issue was discussed in an executive session at a board meeting in May, Miller said maintaining safe infrastructure is a primary obligation of government.

“I have long been very vocal about road repairs, and that it’s the obligation of the county to ensure the safety of our residents,” she said.

Miller said keeping roads in safe condition could potentially save the county from having to pay legal fees resulting from lawsuits.

“I believe lives are at stake,” Miller said.

The state has addressed the issue of crossover collisions on I-10 in the past. ADOT’s 2007 “Strategic Highway Safety Plan” recommends installing “median cable barrier at accident-prone locations” to reduce head-on collisions.

The Federal Highway Administration also recommends installing cable barriers in areas where crossover collisions occur frequently.

Leader, Glazer’s attorney, said the stretch of I-10 where her accident occurred clearly comes under that recommendation, and that the jury in the original case felt the same when it awarded her $7.8 million.

Contact reporter Patrick McNamara at 573-4241 or pmcnamara@tucson.com. On Twitter @pm929