olemus
ÕS: õigussuhtes osaleja

Law Insider:
the holder of the rights and obligations under the law which can be either individuals (persons) or legal entities (companies, organizations, institutions)

ülevaateid
http://baripedia.org/wiki/The_elements_of_the_legal_relationship

https://encyclopedia2.thefreedictionary.com/Subject+of+Law

https://elibrary.law.psu.edu/cgi/viewcontent.cgi?article=1117&context=jlia