A new law designed to curtail instances of children left unattended on school buses hit close to home after an incident earlier this month in which a 4-year-old was left alone on a Unit 5 school bus.

Call it No Child Left Behind — on a bus.

Opponents of the measure who argued, “You can’t legislate common sense,” might be right.

But you can punish a lack of common sense.

And that’s one of the things Senate Bill 932 does. Bus drivers who fail to follow procedures for post-trip bus inspections face a three-year suspension of their permit to drive a school bus.

State law already called for school districts to have policies in place requiring school bus drivers to check for the children or other passengers left on the bus at the end of a shift or work day.

But the law had no teeth.

School districts should be able to handle such situations themselves. They can establish a policy that calls violation of such policies a firing offense. But they can’t suspend a bus driver’s permit. They can’t keep them from getting a job elsewhere, especially if the other district doesn’t check why they left a previous job.

Is a three-year suspension too harsh? Perhaps.

But we aren’t interested in punishing people after the fact as we are in motivating them to follow procedures in the first place. If the potential suspension provides better motivation to thoroughly check a bus, perhaps we will stop hearing about incidents such as the one in Unit 5 or a similar case in a Chicago suburb earlier this year which prompted this law.

The new law also requires school buses to have two-way radios.

As an unfunded state mandate, that requirement also prompted opposition. State Rep. Dan Brady, R-Bloomington, and state Sens. Bill Brady, R-Bloomington, and Dan Rutherford, R-Chenoa, all cited the unfunded mandate in explaining their “no” votes on the bill.

The principle of opposing unfunded state mandates is laudable. These days, the state isn’t even paying in a timely manner for what are supposed to be funded mandates.

However, in this bill, the overall good outweighs possible cost. Many school buses already have two-way radios. It’s a matter of keeping children safe. Districts shouldn’t wait for the state to assume such costs.

It all comes down to this: Despite existing laws and school policies — and despite relatively simple steps that can be taken — children are still being left alone on school buses.

This law may not eliminate that, but it should reduce the occurrence and weed out drivers who aren’t responsible enough to look after our children every day.