Copyright is protected by the Copyright Act. Copying is illegal unless it is permitted by sections 29 and 30 of the Copyright Act.
There is no law against plagiarism. However, "plagiarism violates ethical standards in scholarship" (254).
Publication Manual of the American Psychological Association. 7th ed., American Psychological Association, 2020
Perhaps worst of all "plagiarists are seen not only as dishonest but also as incompetent, incapable of doing research and expressing original thoughts" (7).
MLA Handbook. 8th ed., Modern Language Association of America, 2016
A plagiarist may also be a copyright infringer if the copying is not permitted by the Copyright Act.