The duration of copyright was in the early printers' privileges for a short term, as for seven years, except in France, where copyrights were in perpetuity until the act of the National Assembly; in modern times the copyright term has been lengthened until a term extending through and beyond the life of the author has been adopted by thirty-seven countries, or more than half of those which have copyright laws, of which four assure perpetual copyright. The Constitution imposes only one limitation on the comprehensive rights of authors, in the provision that protection shall be "for limited times" only. This provision has made the discussion of perpetual copyright purely academic in this country. The new American code adopts the double term of twenty-eight and twenty-eight years, making fifty-six years in all, without reference to the life of the author. {Sidenote: Previous American practice} The American law previous to 1909 provided for a uniform term of twenty-eight years, dating from the time of recording the title, with a renewal of fourteen years, securable only by the author, or, if he be dead at the expiration of the term, by his widow or children. No other heirs or persons could renew. The new code differs in making the renewal period a second twenty-eight years and extending the right of renewal to the executors or next of kin and to the proprietors of composite or other impersonal works; but it still denies renewal to assignee proprietors of personal works. {Sidenote: Term in code of 1909} The American code of 1909 provides (sec. 23) "that the copyright secured by this Act shall endure for twenty-eight years from the date of first publication, whether the copyrighted work bears the author's true name or is published anonymously or under an assumed name," and makes provision also in the cases specified for renewal for a second period of twenty-eight years, provided that renewal application is registered in the Copyright Office "within one year prior to the expiration of the original term of copyright." {Sidenote: Renewal}