DWI can be a felony if the defendant has been found guilty twice before of DWI or a related charge, driving with an elevated blood-alcohol level. Exceptions:

- A past plea deal that was reduced to a lesser charge, such as careless or imprudent driving.

- DWIs from municipal courts whose judges aren't licensed lawyers. It's rare, but some towns elect or employ non-lawyers.

No felony charges

Some repeat offenders who qualify for felonies aren't being charged.

To figure out how many, the Post-Dispatch analyzed state data on DWI arrests in 2008. It took the last 10 years of driving records of everyone arrested and determined that at least 275 people in the St. Louis area qualified.

The newspaper reviewed case files and consulted with prosecutors, and found records of only 170 people who had been charged with felonies by July 1. That left 105 arrests, or 38 percent, that were not charged as felonies.

Reason No. 1 - Poor data

Arresting officers commonly use two databases to figure out someone's background.

One police database doesn't always contain conviction information from courts, so officers can't tell if a DWI arrest resulted in a DWI conviction. The other database, run by the Department of Revenue, doesn't list the special plea deals that are crafted to keep DWIs off driving records.

Recognizing the problem, the highway patrol began a third database to track every DWI case from start to finish. But it's optional, and many places don't enter their cases.

Reason No. 2 - Confusing laws

In Missouri, people can be found guilty of a crime and yet not be convicted of anything. They're instead put on a special probation that erases the guilty plea from public view if they satisfy the conditions.

It's called a suspended imposition of sentence (or SIS), and it's used for a significant number of DWI defendants, particularly first-timers.

The Legislature insisted these deals count as prior DWIs if the defendant drives drunk again. But the statute was so poorly written that the state Supreme Court ruled last year that SIS cases from municipal courts couldn't count.

Lawmakers rewrote the law to go back to counting all SIS cases, but the law didn't go into effect until this summer. Officers were left unsure of what prior cases counted, and when.

Reason No. 3 - Busy, busy, busy

For felony charges to be filed, officers meet with prosecutors one on one. In St. Louis County, appointments are routinely booked three to four weeks in advance. Officers can arrive unannounced on "walk-in" days, but lines can stretch for hours.

Sometimes officers leave departments and cases aren't filed at all.

Reason No. 4 - Prosecutor rejects

Prosecutors insist they accept legitimate cases sent their way, but the newspaper has found several times when prosecutors declined to file felony charges for arrests that qualified. Although some departments gripe about rejects, it's hard to document how often it happens.

Reason No. 5 - legal burdens

It's not enough that police databases or driving records indicate someone has a prior DWI. The law requires authorities to get certified copies of the conviction.

Police or prosecutors ask courts, which in practice should be as simple as sending a fax. In reality, with so many municipal courts dotting the area, it can take weeks or months to get responses, with some courts ignoring repeated letters for records.

Lawmakers had another requirement, too: The certified copies had to prove that the defendant had an attorney for the case, or waived the right to have an attorney. The Legislature just got rid of that requirement this summer, but the requirement for certified copies still holds.

Same problems in Illinois?

Perhaps, but nobody knows the extent. Unlike Missouri officials, Illinois Secretary of State Jesse White's office refused to provide the newspaper with data on everyone arrested for DUI there. White's office cited the privacy rights of drunken drivers and an internal secrecy rule to keep the public from seeing such lists.

Consequently, the newspaper was unable to analyze drunken driving cases in Metro East counties.

Reforms to date

After publicity over problems, St. Louis County prosecutors asked all departments to send them any DWIs that might qualify for felonies so prosecutors could seek appropriate charges.

St. Louis County police now do that. County police also double-check all arrests monthly to ensure charges are sought. But those procedures are not uniform across the region.