A year ago I wrote about Ammaria Johnson, a first-grader in Chesterfield, Va., who ate a peanut at recess, broke out in hives immediately, went into anaphylactic shock within minutes, and died after being rushed to the hospital. What could have saved her was right at hand: a relatively inexpensive device called an EpiPen. Because it was prescribed to another child, however, the school nurse couldn’t use it.

The Virginia legislature sprang into action. In April it passed legislation that corrected the rules that prevented school officials from treating Ammaria on the spot. Local school boards now must keep EpiPens on hand that can be used on any student. Other states have passed similar laws, and U.S. senators Dick Durbin and Mark Kirk, a Democrat and Republican from Illinois, have introduced a bill in Congress to get all states to follow suit.

As rare as it is to find a responsive legislature, it’s sadly easy to find prosecutorial misconduct, despite prosecutors’ sworn duty “to seek justice, not merely to convict.”

In 2008, Sen. Ted Stevens, an Alaska Republican, was put on trial for not reporting gifts, mostly renovations to his modest house. He was so convinced of his innocence — he’d paid $160,000 to contractors for their work, far more than experts would testify it was worth — that he asked for a quick trial to remove the cloud over his head before the election in November.

Instead, justice took a back seat to ambition. If you indict a sitting senator, you had better convict a sitting senator. Stevens was found guilty just days before voters went to the polls, largely because the prosecutors let their crucial witness lie on the stand and hid evidence. Stevens lost re- election by about 1 percent of the vote.

The verdict was eventually overturned, and a court- appointed special counsel issued a damning report indicting prosecutors for premeditated “concealment of significant exculpatory evidence, which would have independently corroborated Sen. Stevens’ defense and his testimony, and seriously damaged the testimony and credibility of the government’s key witness.”

Stevens never got the satisfaction of reading that report. He was killed in a plane crash in August 2010. There was another casualty: Prosecutor Nicholas Marsh hanged himself at home shortly after the report was released.

If a senator can’t stand up to ambitious prosecutors, think how hard it is for the rest of us. Or just go see the new documentary West of Memphis, about one of the worst cases of prosecutorial misconduct in U.S. history. It was a case that no one wanted to touch — including former presidential candidate and Arkansas governor Mike Huckabee. It took 18 years, three prior documentaries and attention from celebrities to get three men out of prison for murders they did not commit.

After three 8-year-old boys were killed in 1993 in West Memphis, Ark., passions were high, and the police and prosecutors wanted a conviction. The trial was riddled with perjured testimony, ignored alibis, shoddy forensic work, suppressed evidence, a forced confession, an inept judge and incompetent defense lawyers. One man, Damien Echols, was sentenced to death as a result of the trial, while two others, Jason Baldwin and Jessie Misskelley, received life sentences.

Appeals were unsuccessful. Even when DNA tests exonerated the men in 2007, the state stood by its conviction. (Many of the officials involved in the trial had won judgeships or, in one case, a seat in the Arkansas State Senate.) In 2011, having attracted talented and prominent defense lawyers, the men were finally released.

Two of the most tired cliches in politics are that prosecutors are well-intentioned and legislators are lazy. The good news, and the bad news, is that neither is always true. Most of the time, maybe, but not always.