Over the past several months, the culture and politics of 1990s America has seemed as much under the legal microscope as the horrific details of the Menendez brothers’ crimes and what witnesses described as the exemplary lives they led in prison ever since.

At times, putting that decade on trial felt like a legal strategy by the brothers’ lawyers. In court, their lawyer Mark J. Geragos often invoked the criminal justice policies of the era — punitive long sentences and laws that mandated harsher sentences for repeat offenders, increasing the prison population — and argued that under today’s mores the brothers merited a second chance.

When the brothers stormed into the den of their family’s Beverly Hills mansion in the summer of 1989 and killed their parents using shotguns, Los Angeles was on the cusp of a tumultuous era. By the time the brothers went on trial for the first time, in 1993, the city was still reeling from the deadly riots that followed the acquittal of the police officers in the Rodney King case.

The first trial was one of the first to be televised gavel to gavel to a national audience and foreshadowed the public’s obsession with the O.J. Simpson trial, and the explosion of true-crime programming today. The brothers were tried together but each with his own jury. They asserted that they had been molested by their father and had killed out of fear. Neither jury could reach a verdict, so a mistrial was declared.

By the time the brothers’ second trial began, just after the acquittal of Mr. Simpson in 1995, the judge changed the rules, banning cameras in the courtroom and limiting testimony about sexual abuse. The changes were seen at the time as a reaction to the acquittals of Mr. Simpson and the officers in the Rodney King case, which had embarrassed law enforcement officials. (Years later, a federal appeals court judge suggested that the rules were unfairly changed to improve the chances of a conviction.)

Without being able to consider a lesser charge of manslaughter, as the jurors in the first trial could, the jurors convicted the brothers of murder and effectively sentenced them to life without parole.

“It was clear politics had a major impact on the second trial,” said Robert Rand, who has covered the case since 1989 and has written the book, “The Menendez Murders.” “Because the D.A.’s office had suffered a string of major high-profile case defeats.”