Initially, the Exclusion Act had restricted only new Chinese immigration. But two years later, in 1884, Congress amended the act, now permitting only those Chinese laborers who had lived in the United States before November 1880—the date of the last treaty signed with China—the right to travel freely between the two countries. A special certificate was issued promising the émigré that should he leave, he would be guaranteed the right to return. So for those laborers who had arrived before this date, travel out of the country was still an option. But then in 1888, only a few years after amending the Chinese Exclusion Act, Congress broke the promise the United States had made to the earlier-arriving group by passing the Scott Act, which canceled all certificates granting Chinese laborers their right of reentry. Twenty thousand Chinese who had the misfortune to be out of the country when the legislation was enacted were unable to return, despite the previous guarantee from the United States government and the fact that many owned property and businesses here and had families here as well. At the very moment the law went into effect, some six hundred Chinese were on their way back to the United States with government-issued certificates granting them the right of reentry, yet they were not allowed to disembark. (Chang 135)