A comma costs a cable company $1 million

As we know, non-restrictive phrases or clauses -- that is, those that can be dropped out of a sentence without changing its meaning -- are set off in commas.
So, the second comma in the following sentence makes the "and .. " adverbial phrase a non-restrictive element, which means that the contract can be terminated in a year:
“This Agreement shall be effective from the date it is made and shall continue in force for a period of five (5) years from the date it is made, and thereafter for successive five (5) year terms, unless and until terminated by one year prior notice in writing by either party.”

Here's the whole story from a year ago:

By Ian Austin of The New York Times

OTTAWA, Oct. 18 - What is the price of an extra comma? For Canada’s largest cable television company, it may be 1 million Canadian dollars.
Rogers Communications of Toronto and a telephone company in Atlantic Canada are locked in an arcane grammar debate that will decide the fate of a contract between the two corporations.
Canada’s telecommunications regulator, citing what it called the “rules of punctuation”, recently ruled that a single comma in a 14 page contract allows Bell Aliant to cancel a five year contract covering use of telephone poles by Rogers at any time with notice.
Rather than accept the regulator’s grammatical parsing, Rogers has now turned to Canada’s official language, French, as well as its own outside grammar expert to appeal the ruling. The case clearly frustrates Kenneth G. Engelhart, its vice president of regulatory affairs.
“Why they feel that a comma should somehow overrule the plain meaning of the words is beyond me,” Mr. Engelhart said. “I don’t think it makes any sense.”
The agreement between the two companies is a standard contract for the use of utility poles that was negotiated between a cable television trade association and an alliance of telephone companies. French and English versions of the contract were approved by the government regulator about six years ago.
Mr. Engelhart said that the cable industry’s has always understood that the pole contracts run for five years. In that industry’s view, the contracts then automatically renew for another five years unless a telephone company cancels the agreement before the start of its final 12 months.
Aliant, which is controlled by Montreal-based BCE, declined to comment on the dispute. However, in a filing with the Canadian Radio-television and Telecommunications Commission, it declared the issue “a classic case of where the placement of a comma has great importance.”
Mr. Engelhart said the grammar fight began when Aliant told Rogers in February 2005 it was canceling a pole agreement for the province of New Brunswick one year early. The cancellation was necessary because a local electrical utility was taking direct control of poles that Aliant previously managed on its behalf.
The power company, Mr. Engelhart said, planned to “really crank up rates,” a change that would cost Rogers about 1 million Canadian dollars over that final year.
In the first round, the regulator agreed with Aliant that the second comma in this sentence enables the phone company to escape the contract after as little as one year: “This Agreement shall be effective from the date it is made and shall continue in force for a period of five (5) years from the date it is made, and thereafter for successive five (5) year terms, unless and until terminated by one year prior notice in writing by either party.”
Even Aliant allowed in its submissions that there are at least three different ways to interpret the sentence.
But the regulator concluded the second comma means that the part of the sentence describing the one year notice for cancellation applies to both contract’s five year term as well as its renewal.
“The meaning of the clause was clear and unambiguous,” it wrote in a ruling issued in July.
Mr. Engelhart acknowledged that his lawyers may have underestimated the regulator’s interest in grammar.
“We were obviously too confident the first time around,” he said.
To bolster its appeal, Rogers commissioned a 69-page affidavit, mostly about commas, from Kenneth A. Adams, a lawyer from Garden City, N.Y. and the author of two books on contract language. It disputes the regulator’s analysis of what Mr. Adams calls “The Rule of The Last Antecedent.”
Rogers is also banking on the official French version of the pole agreements which has equal status under Canadian law. While differences between the languages means that it will not settle the comma question, Mr. Engelhart said its phrasing removes any ambiguity about the contract’s lifespan.
“It becomes very clear once you read the French version,” he said.