While it seems few if any civil governments today enforce the holy Sabbath (which is to be kept on the first day of the week), the nation of Tonga still understands God's requirement to prohibit work on the Lord's Day. In Tonga's Constitution, part six of the Declaration of Rights reads:The following from a book on Tonga summarizes what is and isn't permissible in Tonga on Sunday (at least, presumably, in 2001, when the book was published):
Sabbath Day to be kept holy The Sabbath Day shall be kept holy in Tonga and no person shall practise his trade or profession or conduct any commercial undertaking on the Sabbath Day except according to law; and any agreement made or witnessed on that day shall be null and void and of no legal effect.
Interestingly, some hold that Tonga's Sunday should be a Saturday, due to Tonga's position on the time zone:Buses don't operate, businesses are closed, sports events are prohibited and planes may not land. Contracts signed on Sunday are considered null and void and any Tongan caught fishing or guilty of any other breach of the Sabbath is subject to a T$10 fine or three months' hard labour. Even swimming at the beach is a no-no on Sunday for Tongans.
Bakeries are the only shops allowed to open on Sunday afternoon thanks to an emergency law that was enacted after a devastating cyclone in the 1980s and never repealed. A few restaurants and tourist facilities open and the odd taxi is available, but that's about it. What most people do on Sunday is go to church.
Because Tonga and Samoa lie east of the 180th meridian, both countries should logically be in the same day. But Tonga wanted to have the same date as Australia and New Zealand, so the line was drawn arbitrarily east of Tonga, putting it 1 day ahead of Samoa.
To travelers, it's even more confusing because the time of day is the same in Tonga and Samoa. When traveling from one to the other, only the date changes. For example, if everyone is going to church at 10am on Sunday in Tonga, everyone's at work on Saturday in Samoa.
 Read Tonga's Constitution here
 Matt Fletcher and Nancy Keller, Tonga (4th Edition) (Australia: Lonely Planet Publications Pty Ltd, 2001), 30. "The People," Frommer's (John Wiley & Sons, Inc., 2000-2013). Retrieved January 1, 2013.
Note about the Theonomy Applied Series: In quoting any particular law, we do not necessarily endorse every aspect of that law as biblical, whether it be the prohibition, sanction, court procedure, etc. Rather, we are merely showing the more or less attempt to apply biblical law in history, whether or not that application was fully biblical. Moreover, in quoting any particular law, we do not necessarily consider those who passed and/or enforced such a law as being fully orthodox in their Christian theology. Professing Christian rulers in history have ranged in their theology from being orthodox (that is, Reformed Protestants) to heretical (for example, Roman Catholics).