Several of the richest and most powerful plaintiffs' attorneys in America may soon be shuffling off to federal prison - further tarnishing the negative image surrounding trial lawyers.

Class-action tort king Melvyn I. Weiss pleaded guilty last week to federal criminal charges related to his role in a scheme to give kickbacks to plaintiffs in lawsuits filed by his firm, Milberg Weiss.

One of Weiss' former partners, William S. Lerach, was sentenced last month to two years in prison after pleading guilty to his role in the scheme.

Then this bombshell hit: Richard F. "Dickie" Scruggs pleaded guilty March 14 to trying to bribe a judge in Mississippi. Scruggs burnished his reputation as one of the most feared lawyers in the country after taking on Big Tobacco and reaching a $206 billion settlement in 1998 on behalf of 46 states. The case was the subject of the movie

The Insider.

In the world of trial lawyers, the trio of convictions was like finding out that Ruth, Gehrig and Mays took steroids and fixed baseball games.

In their own way, Weiss, Lerach and Scruggs played Davids to business Goliaths. They took on entire industries, winning hundreds of millions of dollars in settlements from companies for aggrieved individuals.

Some suits brought about positive change in corporate behavior and improved product safety. Along the way, the lawyers pocketed millions in fees and became fabulously wealthy.

Weiss and Lerach almost single-handedly invented the securities class-action suits, often filing claims after a company's stock tanked or bad news hit.

Scruggs, meanwhile, revolutionized American tort law, by rounding up thousands of plaintiffs to take on major businesses and industries, including cigarette makers, drug companies and construction firms. The crush of litigation often forced companies into major settlements.

Trial lawyers across the country learned from them and followed their lead. Each man became the scourge of many corporate corner offices, which were forced to spend time and money battling legal claims the companies often deemed frivolous.

But plaintiffs' attorneys argued that their legal action filled a regulatory void and helped to keep Big Business in check.

There's a little bit of truth to both sides.

Just consider the tangled mess surrounding asbestos litigation, which has dragged on for decades. Thousands of individuals who were harmed or died from asbestos have received some financial compensation. But many of the claims have proved to be bogus, cooked up by sleazy lawyers, aided by shoddy doctors.

The same goes for silicosis litigation, where a federal judge ruled in 2006 that thousands of claims had been manufactured for money.

The lesson here is that the trial lawyers play a key role in our legal system. But in pursuing fraud, the trial lawyers can't commit fraud.

Many state courts and the Supreme Court have issued recent rulings that amount to major setbacks for the plaintiffs' bar. But it's hard to rally support for trial lawyers when the leaders of the field are going off to prison.

The trial bar has long been held in low esteem in polls. All the more reason why attorneys must maintain high ethical standards when representing individuals and companies.

Weiss, Lerach and Scruggs did lots of good in their day. But they got greedy and broke the law.

Now, it's their turn to pay up.