It is welcome news that state Attorney General Tom Corbett has said his office will launch a formal investigation into the $3.7 million in legislative bonuses awarded by Democratic and Republican leaders in the House and Senate in 2005 and 2006.

For too long, Pennsylvania's legislative leaders have used special accounts at their disposal to spend millions of dollars of taxpayers' money with no transparency and little accountability. The Corbett investigation will focus on whether the bonuses were paid for political work done in re-election campaigns, because it is illegal to use taxpayer funds for political work.

News reports of the year-end bonuses, which topped out at more than $25,000, attracted the attention of many, including reform advocates and even some state lawmakers who urged Corbett's office to investigate.

House Democrats generated the most news because their bonus payments jumped to $1.9 million in the 2006 election year, compared with $435,000 in 2005, a non-election year.

It didn't help curb suspicions of misuse when House Majority Leader H. William DeWeese initially refused to reveal the bonuses, saying it was an "internal personnel matter."

Then, after suggesting that the bonus payments were nobody's business (other than his own), DeWeese estimated that the bonuses amounted to about $400,000. But when public pressure soon forced a full release of the House Democrats' bonus program, it was revealed that the total was $1.9 million in 2006 and $435,000 in 2005.

Even Gov. Ed Rendell, who shouldn't be shocked by government spending, called the bonuses "stunning."

The money to pay the bonuses came out of four separate $50 million "leadership accounts" and the now-public payment records reveal that in many cases the bonuses jumped dramatically in 2006, which just happened to have been a tough election year in which Democrats made dramatic gains.

Corbett's office will be looking for any connection between bonuses and purely political or campaign-oriented work, because the law prohibits using taxpayer dollars to pay legislative aides for political work.

Senate Republicans, at least, have said they will end the practice of handing out year-end bonuses. But ending the practice is not enough.

It is appropriate for the Attorney General's office to investigate these legislative bonuses. But proving that bonus payments were for political work might be difficult, so Corbett is suggesting that incriminating e-mails or, better yet, whistleblowers who come forward with firsthand knowledge of the bonus program will be important elements in building a case. Reform-minded lawmakers might want to consider creating a reward program (perhaps funded with money from leadership accounts) for whistleblowers to come forward.

The big bonuses paid out of the leadership accounts are just another example of the culture of entitlement and the lack of accountability that exists in Harrisburg, at least among most entrenched party leaders. Exposing the bonus program and the broader spending practices of party leaders is one small step toward changing the culture in Harrisburg.

Other investigations are warranted if Harrisburg's culture is to be changed; an in-depth probe of the legislative bonus payment program is as good a place to start as any.