Self-Plagiarism is reusing text or data without citation and representing it as "new"

Though self-plagiarism is not considered research misconduct (42 CFR Part 93), it is a poor practice for several reasons.  It is contrary to the spirit of good scholarship because it represents content in a publication as new without citing previous publication.  This is considered deceptive and should be avoided. Redundancy also results in an inconsistent record that is difficult for other researchers to use and cite correctly.  Since authors often assign copyright of the completed paper to the publisher, submitting the same material to additional publishers will infringe on the original copyright.  It may also be flagged by publishers during the review process and result in delayed publication.  As a best practice, all previously published work should be cited.

Determining authorship

From International Committee of Medical Journal Editors (ICMJE) - Defining the Role of Authors and Contributors:

Authorship should only be credited to those who have contributed in a way that satisfies one of the following criteria:

• i)    “Substantial  contribution  to  the  conception  or  design  of  the  work;  or  the  
  acquisition,
  analysis, or interpretation of data for the work; and
  ii)    drafting the work or revising it critically for important intellectual content; and
  iii)    final approval of the version to be published; and
  iv)    agreement to be accountable for all aspects of the work in ensuring that questions related 
  to the accuracy or integrity of any part of the work are appropriately investigated and
  resolved.”

https://www.icmje.org/recommendations/browse/roles-and-responsibilities/defining-the-role-of-authors-and-contributors.

Multi-author publications have become the norm in recent years.  Studies have shown that this can be attributed to the emphasis placed on publishing peer reviewed papers and the citation metrics used for academic advancement.  One outcome of the increasing numbers of authors credited is less accountability and increasing numbers of authorship disputes.  Some of the issues that contribute to authorship disputes (Sethy, 2020) include:

• Authors who feel that they should be credited have not been
• Non-contributors are listed as authors without their consent
• Disputes over first and last author status
• Withdrawing from the listed authors following review, especially when their contributions are criticized or the prestige of the journal is considered to be unsatisfactory.

Sethy, S.S. Responsible Conduct of Research and Ethical Publishing Practices: A Proposal to Resolve ‘Authorship Disputes’ over Multi-Author Paper Publication. J Acad Ethics 18, 283–300 (2020). https://doi.org/10.1007/s10805-020-09375-0  

Unethical Authorship 

Two types of unethical authorship:

• Individuals who meet the criteria for authorship are not listed as authors (ghost authors).
• Authorship credit is given to those who have not made significant contribution and do not meet the criteria for authorship. (guest authorship, honorary authorship or gift authorship.)

Ghost authorship is when an author asks not to be included either because of disputes with collaborators, perceived low quality of the results or conflict of interest.  Guest authorship commonly occurs when authors are trying to increase the visibility of the paper through inclusion of an established scholar.  Honorary authorship is when senior academics are included as recognition of their position or past work and gift authorship may be a way of acknowledging support or mentorship that did not directly contribute to the body of work.  

Recognizing contributors through CRediT (Contributor Roles Taxonomy)

In an effort to provide better attribution to the full range of contributors to a research product, a taxonomy was created in 2014 that described 14 different roles.    CRediT, or the Contributor Roles Taxonomy, has been formalized as an ANSI/NISO standard as of February 8, 2022 and has been adopted by over 50 organizations representing thousands of journals.  When submitting an article for publication, the corresponding author should list all the contributions from authors and those usually listed in acknowledgements.  It is possible for contributors to have multiple roles and the degree of contribution can be designated as "lead", "equal" or "supporting."  

Some of the advantages to adopting CRediT include:

• Reducing potential for author disputes
• Encouraging visibility for a wide range of contributions
• Improved tracking of individual contributions
• Recognition of the contributions of support personnel such as statisticians, analysts or librarians

Contributor Roles Taxonomy - more information