As you have asked about the Law Distance Learning Diploma courses after BCA, there are some universities who offer some of these courses
IGNOU Law distance learning programs:

Doctoral Degree
Doctor of Philosophy in Law (PhD in Law)
PG and Advance Diploma
Post-Graduate Diploma in Intellectual Property Rights (PGDIPR)
Post Graduate Diploma in Criminal Justice (PGDCJ )
PG and Advance Certificate
Post Graduate Certificate in Cyber Law (PGCCL)
Post-Graduate Certificate in Patent Practice (PGCPP)
Diploma
Diploma in Paralegal Practice (DIPP)
Certificate
Certificate in Human Rights (CHR)
Certificate in Consumer Protection (CCP)
Certificate in International Humanitarian Law (CIHL )
Certificate in Anti Human Trafficking (CAHT )
Certificate in Co-operation, Co-operative Law (CCLBL )


Tamil Nadu Dr. Ambedkar Law University Distance learning programs:

PG Diploma in Business Law (P.G.D.B.L.)
PG Diploma in Environmental Law (P.G.D.E.L.)
PG Diploma in Information Technology Law (P.G.D.I.T.L)
PG Diploma in Intellectual Property Law (P.G.D.I.P.L.)
PG Diploma in Labour Law (P.G.D.L.L.)
PG Diploma in Human Rights & Duties Education (P.G.D.H.R. & D.E.)
PG Diploma in Law Librarianship (P.G.D.L.L.)
PG Diploma in Consumer Law and Protection (P.G.D.C.L. & P.)
PG Diploma in Cyber Forensic and Internet Security (P.G.D.C.F. & I.S.)
PG Diploma in Criminal Law, Criminology and Forensic Science (P.G.D.C.L.C. & F.S.)
PG Diploma in Medico – Legal Aspects (P.G.D.M.L.A.)
PG Diploma in Maritime Law (P.G.D.M.L)