Seems like a weird law, but why does every sweepstakes contest I’ve ever seen say “no purchase necessary?” Isn’t the whole point to encourage consumers to buy their products by providing them with a bonus?
I’m sure it has something to do with corruption and state-run lotteries, but I’ll leave it to the enlightened Dopers herein to illuminate me. 
Esprix
I believe it is to make it a true “giveaway.” If you were required to put money down in order to win, that could be (I suppose) defined as gambling.
WAG quotient of this answer: 66.6%
That’s what I always heard. If you have to pay for the opportunity to win something, it’s a lottery. Lotteries are gambling.
I’m curious if anyone’s ever won a huge prize without purchasing the corresponding product?
I think the point is to keep the sweepstakes separate from actual gambling. The state doesn’t want people lured into buying stuff they don’t really want just to try to win the prize.
Often times though, in order to enter the sweepstakes without buying something, you have find the fine print somewhere that explains how to jump thru some hoops: like mailing them a request for an entry blank (along with a SSAE), then filling out the form when it arrives several weeks later, and then mailing it back.
But having the sweepstakes does generate excitement for the product, so most people play the sweepstakes by buying the product instead of the “no purchase necessary” technique.
When I get sweepstakes in the mail, I like to find the odds of winning. The longest odds I’ve seen was 1 out of five-hundred million.
Oh heavens yes. Certainly. There are newsletters entirely devoted to helping people enter contests without purchase. There are many people, my mom included, that spend a great deal of their time entering contests, early and often. My mom spends probably five hours a week doing this, and she wins maybe three things a month, usually small stuff like autographed footballs or totebags or hats. But then every once in awhile she get something good, like $5,000 cash and a trip to Florida.
From the reading the USPS site, it is because requiring a purchase would make it a lottery as defined by most state laws, hence making them illegal.
http://www.usps.com/cpim/ftp/pubs/pub546.htm
for more info
The corollary to my earlier post is that whoever is running the contest cannot make a distinction between entries made by purchase, and enteries made without purchase. If purchasing gave you an advantage, then it would be illegal. See “Publisher’s Clearing House, Misconceptions About.”
Oops, I meant to say 1 out of five-hundred Billion.
I meant, did anyone ever win a huge ($500,000+) prize by sending in for a free entry, and not even buying the soda/cookies/gum whatever…
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Has anyone ever not been able to participate in a sweepstakes because they lived in a “void where prohibited” area?" As far as I know my state (Idaho) has never been considered a “void where prohited” zone for any contest I’ve entered. If it is prohibited in any area, then why?
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Along the same lines, I’ve noticed that sweepstakes SOMETIMES include an incredibly easy “trivia” question in order to comply with Canadian laws.
I gather that the inclusion of a question makes the promotion a “contest” rather than a lottery, and this gives the promotion more leeway under Canadian law.
I don’t know where you livin’ but $500,000+ is pretty darn rare. You have your Publishers’ Clearing House, and your McDonald’s Monopoly game, but beyond that there are very few contests that award anything upward of $10,000 or a car or a jetski or a “lifetime supply” of something. Read the wrappers.
The answer to your question, however, is academic. The probability of you winning by buying something is the same as if you were to send off for a gamepiece. If you’re asking for figures on what percentage of contest entrants enter by purchasing something, I imagine that varies pretty widely. Maybe someone can come along and help.
I can’t rightfully count this as a cite, but over at www.dumbwarnings.com, they have a listing for a Fritos sweepstakes:
“You could be a winner! No purchase necessary. Details inside.”
And I think I remeber actually seeing this in stores.