Earlier this week, I wrote to you all to tell you that the package of driving reform bills was falling apart in the state Legislature.

Many of you wrote back with a simple question: How?

Well, now we have the latest casualty. And we have an answer to that question, at least for what was probably the most promising potential reform.

Reporters Robert Lewis and Lauren Hepler have a new story out showing how lawmakers used what’s known as a “hostile amendment” to gut a DUI reform that had widespread support in Sacramento.

The bill would’ve mandated that anyone convicted of a DUI use an ignition interlock device – those in-car breathalyzers – to ensure they don’t drive drunk. It wasn’t a revolutionary bill: It would have simply brought California in line with most states.

The Senate Appropriations Committee gutted the bill. It’s led by state Sen. Sabrina Cervantes.

Cervantes, you might remember, was arrested for a DUI in Sacramento last year, but prosecutors chose not to press charges after a blood test found she had “no measurable amount of drugs or alcohol in her system.” (She later sued the Sacramento Police Department, arguing the arrest was discriminatory and in retaliation for her legislation restricting police data collection.)

Her sister, Riverside City Councilmember Clarissa Cervantes, has two DUI convictions.

So far, we have gotten little explanation as to why the bill was gutted. Its supporters are scrambling to salvage the legislation.

We’ll keep you updated.