The federal government could take a cue from its regulation of charitable organizations in monitoring the freewheeling fiscal habits of big-time college athletics, a leading tax lawyer says. The author reports on the ideas offered by John D. Colombo, a professor at the University of Illinois College of Law, for monitoring big spending on college sports. Mr. Colombo's comments came at a meeting of the Knight Commission on Intercollegiate Athletics, where college presidents and other members gathered to discuss fiscal responsibility in college sports. Critics of big spending on sports have questioned the tax-free status enjoyed by colleges and the National Collegiate Athletic Association, and have called for federal lawmakers or the Internal Revenue Service to revoke their tax exemptions. But Mr. Colombo recommends a subtler strategy. And the model may be found in the current regulation of charities, said the professor, who is a frequent adviser to Congress on matters of tax exemption.