The march of technology is threatening to trample a time-honored legal guarantee for authors and artists. Copyright laws - legislative protection for the originators of everything from music to movies - are coming under increasing pressure as technological innovations make the reproduction of printed and filmed material a relatively simple task.
''Copyright law was never meant for the electronic age,'' says Gervaise Davis III, a California lawyer who specializes in copyright law. ''We're trying to stuff 20th-century technology into a 17th-century concept. The legal system still hasn't learned how to deal with the problems technology has created.''
At the core of controversy is the concept of ''decentralization'' - the violation of copyright laws by individuals in the home or at the office, where enforcement is virtually impossible.
One facet of the issue was highlighted in early January. The US Supreme Court heard arguments in the so-called ''Betamax case,'' in which a federal appellate court ruled in 1981 that the millions of Americans who now own videotape recorders cannot use them to tape copyrighted television programs. The high court is expected to rule on the case in late spring.
But the wider copyright problem affects virtually every industry where duplication of a product is technically feasible:
* The recording industry is fighting copyright violations on three fronts: illegal home taping that cost the $4 billion industry an estimated $1 billion in ''displaced'' retail sales last year; ''pirating'' - the retail sale of illegal copies - which cost the industry an estimated $350 million in 1982; and the rise of record rental shops, which are allegedly set up to rent records for illegal home taping. Two dozen such shops existed in Japan in 1980, now there are 1,600 there, and industry observers fear similar expansion in the United States.
* The motion picture industry estimates it loses anywhere from $100 million to $700 million yearly from illegally copied films. That's against $2 billion in revenue for the industry. And losses traceable to the illegal interception of satellite signals for cable movie channels such as Home Box Office are mounting. Many of the film industry's contracts with cable television channels are on a per-subscriber basis - only those viewers who paid to see the movie should be receiving the signal.
* A five-year congressional review of copyright violations, mandated by a 1976 law, concludes that there is widespread illegal copying of books in libraries. The report states that the publishing industry lost $38.6 million last year. Experts say that's a conservative estimate. The Association of American Publishers has financed a number of suits against universities to stop widespread illegal photocopying of whole books or chapters. Recently, nine publishers filed suit against New York University.
* The growth field of computer software manufacturing is being stunted by the loss of an estimated 20 to 30 percent of total revenues because of pirated programs.
''The implications of all this for copyright are horrendous,'' writes Ithiel de Sola Pool, a professor of political science at the Massachusetts Institute of Technology, in a recent issue of Daedalus magazine. ''Indeed, the whole notion of copyright becomes obsolete, for it is rooted in the technology of print.''
Nevertheless, filmmakers, authors, musicians, and artists are fighting back. In the Betamax case, two movie studios are suing Sony Corporation, claiming the Japanese firm should be held responsible for the illegal recording that is being done on the machines it builds.
Increasingly, those whose copyrights are being infringed are targeting the hardware used in illegal copying, or those dealing with large-volume resale of pirated material, rather than individuals illegally taping in their homes. Such private copying appears to be beyond the reach of current laws. A bill that stalled in Congress last year but will be reintroduced in 1983 would place a tax on the blank cartridges used to videotape television programs and record albums.
''Copyright owners seem to be taking the position that maybe not every penny will be paid to them that they think they deserve, but at least the principle will be established and we can take it from there. They see these cases as bargaining chips,'' says Alan Latman, a professor of law at New York University and a partner in the New York law firm of Cowan Liebowitz and Latman.
The Supreme Court's Betamax case could have an impact far beyond videotaping. It could serve as a landmark ruling affecting all areas of copyright law, according to Dorothy Schrader, a general counsel for the copyright office of the Library of Congress.
Although Congress is not likely to act on the several copyright amendments before it until the Supreme Court reaches a decision, many experts say the pressures on copyright law demand political decisions in addition to legal judgments.
After 20 years of debate Congress finally passed a major copyright revision in 1976, the first since 1909. That revision, coupled with a law passed last year that made the illegal duplication of more than 1,000 phonograph albums or 65 movie prints a felony instead of a misdemeanor, has helped give new teeth to the old copyright laws.
The problem is, ''a number of devices and compromises are already out of date. Things are moving too fast,'' Mr. Latman says. But he adds, ''We do have a healthy head start on future problems and a respect for the technology today that was absent in years gone by.''