Who first enjoined Sunday-keeping by law?

Answer

Constantine the Great.
NOTES - "The earliest recognition of the observance of Sunday as a legal duty is a constitution of
Constantine in AD. 321, enacting that all courts of justice, inhabitants of towns, and workshops were to be
at rest on Sunday (venerabili die Solis), with an exception in favor of those engaged in agricultural labor. "Encyclopedia Britannica, ninth edition, article "Sunday."
"Constantine the Great made a law for the whole empire (AD. 321) that Sunday should be kept as
a day of rest in all cities and towns; but he allowed the country people to follow their work."-Encyclopedia
Americana, article "Sabbath."
"Unquestionably the first law, either ecclesiastical or civil, by which the Sabbatical observance of
that day is known to have been ordained, is the edict of Constantine, AD. 321."-Chambers' Encyclopedia,
article "Sabbath."

What is the ground of justification on God's part?
By what name is Christ appropriately called?
11. How is the closing work of the gospel under the outpouring of the Spirit described by the Revelator?
How is the remnant church described?
Who alone knows the exact day of Christ's coming?
In what work are angels engaged?
What universal chorus of praise will then be heard?

Questions & Answers are from the book Bible Readings for the Home Circle