WASHINGTON, D.C.: The debate over indecency vs. free speech flared again as the Supreme Court refused to bar a federal law that requires cable TV operators either to block adult entertainment offerings or to air them only late in the evening. Subscriber-only, sex-oriented networks Playboy Television and Spice Entertainment are challenging the law as a violation of their First Amendment rights and had asked that the law not be enforced while a court decision on their lawsuit is pending. The two companies charge that the exorbitant cost of scrambling their programs has led cable operators to restrict adult sex programs to airtimes between 10p.m. and 6a.m only. Playboy and Spice Entertainment argued that cable customers concerned about the programming can request that cable companies block individual channels from reaching their homes, but to no avail. The Supreme Court has not finished with the prickly issue of indecency and free speech. Coming up next: a ruling on the constitutionality of the Communications Decency Act, a law signed by President Clinton last year that would make it a criminal offense to broadcast explicit materials over the Internet.