Black flexed his muscle to prevent a ban on video poker from reaching the House floor for several years, until his legal troubles forced him to let the ban go through. He slipped a landmark provision into the 2005 state budget that made it much easier for chiropractors to gain patients by putting them on an even footing with family doctors. And he helped his fellow optometrists gain business with legislation that required all children to receive an eye exam before entering school. That legislation created such an outcry that it was later removed.None of these cases would cause much of a stir on Jones Street if it weren't for the measures all three groups took to support Black. State Board of Elections probes found that video poker interests and optometrists provided the speaker with illegal campaign contributions, while three chiropractors slipped him $25,000 in cash and a $4,000 check that he pocketed. On Thursday, Black, 71, a Mecklenburg County Democrat, pleaded guilty to a federal felony corruption charge for accepting the chiropractors' money. He could face as much as 10 years in prison.