Antonin Scalia was the longest-tenured justice on the current Supreme Court. But another quality also set him apart: Among the court's members, he was the most frequent traveler, to spots around the globe, on trips paid for by private sponsors. Ethical standards prohibit judges from accepting gifts from anyone with a matter currently before the court. But those guidelines presented no barrier to John Poindexter, who invited Justice Scalia to stay at his West Texas ranch. Mr. Poindexter is the owner of J. B. Poindexter & Co., a manufacturing firm based in Houston. One of his companies, the Mic Group, was a defendant in an age discrimination lawsuit filed by a former employee who unsuccessfully petitioned the Supreme Court for a review last year. Mr. Poindexter, according to a former general manager at the ranch, is also a leader in the International Order of St. Hubertus, a worldwide organization of hunters, as, apparently, were several other guests during Justice Scalia's visit. In 2011, a liberal advocacy group, Common Cause, questioned whether Justice Scalia and Justice Clarence Thomas should have disqualified themselves from participating in the landmark Citizens United case on campaign finance because they had attended a political retreat in Palm Springs, Calif., sponsored by the conservative financier Charles G. Koch. Mr. Koch funds groups that could benefit from the ruling.