Sixteen federal appeals court judges violated conflict-of-interest regulations during cases over the last three years, a new report from the watchdog group the Center for Public Integrity found. 

The judges' decisions are now being questioned after the report found that 24 cases had judges make a ruling despite owning stock in a company involved in the legal proceedings, the Associated Press reported. The report also found that two other cases had judges who had financial ties with law firms representing the prosecution or defense. The report is to be released Monday.

One violation involved 11th U.S. Circuit Court of Appeals Judge James Hill in a 2011 three-judge case. At the time James owned $100,000 stock in the health care product giant Johnson & Johnson, which was also a party in the 2011 case, the AP reported. The Atlanta-based court sided with a lower court's verdict in favor of Johnson & Johnson in a lawsuit that involved a medication pump that failed to work.

The report found that over half of all appellate judges own corporate stock. However, some do not keep track of their investments. 

"Considering the importance of judicial integrity and avoidance of conflicts of interest, I don't think it is asking too much of a judge to expect him or her to know what his or her holdings are," William G. Ross, a Stamford University law professor, told NBC News. "Even judges with significant portfolios should be familiar with their own holdings."

There are rules judges must follow to prevent conflict violations, including an electronic database system set up in 2006 to avoid conflicts. But the report shows the problem persists. There is no punishment for judges who do not step aside in the face of a potential conflict, according to the AP.

The violations represent a small fraction of the 109,000 cases decided in appeals court during the three-year time period, David Sellers, a spokesman for the Administrative Office of the U.S. Courts, told the AP. The conflicts are simply due to human error, he said.