How will Donald Trump make Mexico pay for the wall? Why does it make sense that Mexico will pay? Will Mexico do it?

Because Mexico is externalizing costs onto the US while receiving in-kind compensation by draining money from the US economy in the form of remittances and forcing the US to spend more money on its border patrol by refusing to police the border.

Also, because while America can play nicely with some criminal aliens, Mexico will throw you in jail, no exceptions, if you illegally enter their country. It would be one thing if Mexico made it legal for US citizens to enter without checking through border patrol, or even turned a blind eye — but they don’t. So Mexico apparently cares about THEIR border integrity enough to prosecute US citizens, which means the US should be given deference to police our border vigorously as well.

Mexico also has let many central Americans, the chief source of illegal aliens in recent years, traverse their country to come over the border. If they are benignly ignoring these constant tests to our sovereignty, then we are absolutely justified to build a wall.

Lastly, Mexico benefits disproportionately from NAFTA, with investment from major American companies giving Mexico pizazz and acclaim on a worldwide stage. These are conditioned, of course, on a good working North American relationship. These constant attacks on our sovereignty are an affront that cannot be ignored, especially while we are actively helping Mexico through trade agreements.

As a Mexican national I propose that we should seriously call Trump on his bluff and Mexico should accept building and paying for the wall - 20 feet taller than his proposal -, We will call it The Tortilla Wall (Mexico will do it, if and only if, Trump gets elected as President/Emperor, which seems impossible today), If He gets elected, We are going to need it anyway in order to keep Americans from fleeing to Mexico once President/Emperor Trump puts all his stupidly insane policies in place.

Just imagine this scenario on his first 6 months in office: President/Emperor Trump imposes 35% or higher trade taxes on China and Mexico and any other countries that become flavor of the month to him (It will immediately create real inflation with increased prices at Target, Walmart and basically all other stores where Americans shop - with the exception of groceries the majority of consumer products are made elsewhere - for the sake of this argument let´s say that inflation grows from 5% to 10% per year, which in turn pushes interest rates from banks - from credit card rates to mortgage rates - to go way up - let´s say double to triple on average - bankers are humans too! - causing a disaster for an economy that is driven by internal consumer spending fueled by bank credit - from clothes to cars to trips Americans live on credit - this will cause major problems for banks causing defaults and very probably a huge mortgage crisis caused by high rates on overextended consumers the likes of which America has Never seen, to add insult to injury, then President/Emperor Trump increases military spending - since apparently $600 billion a year are not enough - (expenses) while reducing Taxes on all Americans (income) - his beautiful, huge tax plan - creating at least a $10 trillion deficit in 10 years plus increased military spending on top of an already super high level of national debt, $21 Trillion and growing - a huge hole - which President/Emperor Trump says is going to be filled with economic growth (2016 total GDP is estimated to be $18.55 trillion, If you are ultra optimistic bordering on delusional - like him - you could say growth will be at most 5% per year on average which means $927 billion per year, which means it will take more than 10 years if everything goes spectacularly well just to get to basically the same level the economy is today! - In the meantime President/Emperor Trump for the length of his terms even if reelected will NOT have enough resources for infrastructure projects or basically any project since He will reduce the government income while keeping or expanding its expenses including not touching the sacred Social Security, Medicaid and Medicare and increasing spending on the Military - which is actually a part of government even if Hannity - Trump´s head muse - does not believe so, and it will be increased because President/Emperor Trump says that He is the most militaristic person - whatever that means -) All this caused by only TWO of his ideas coming from that great, huge, beautiful brain of his!

Now you see how it starts making sense for us Mexicans to accept to build and pay for the Tortilla wall! I can assure you that none of Californians, Arizonans or Texans will ever flee to Canada, it is just too cold!

Just to leave you with a happy thought let me remind you that President/Emperor Trump says that He does not want to have the wall named after him, what He actually wants is a Statue in Washington!!!! He actually said this!, Now if We could just find someone to pay for it…

In your question, you voice some questionable assumptions. That Trump would be required to violate treaties, international law or the Constitution to achieve his goal of a wall is a bit of a stretch. As other have said in their answers, there are several tools at the disposal of our Chief Executive (the President) that could be quite effective and perfectly legal.

The specifics of what the wall would cost or look like are irrelevant to the question. Things like trade agreements, specifically using our trade deficit against Mexico, could be very effective in motivating the Mexican government to play ball. We have other tools, such as the massive debt Mexico owes the US from loans and foreign aid. This is money they are required to pay back over time. Trump could force Mexico’s hand and bump up the timeline.

None of this is to say that there wouldn’t be other dire consequences as a result of pursuing the “Wall policy”. There may well be. We could end up in a trade war that sucks in other North- and South American nations. We could end up with a revolution or civil war on either side of the border. Who knows? But, your question was theoretical, and the theoretical answer is, “YES”, he can do it.

According to both Candidate Trump and President-Elect Trump, “The Wall” will be a physical barrier.

Candidate Trump’s promises:

1. "I will build a great wall, and nobody builds walls better than me, believe me --and I'll build them very inexpensively. I will build a great, great wall on our southern border, and I will make Mexico pay for that wall. Mark my words." http://www.popsugar.com/latina/p....

2. “Trump has said the wall could cost $8 billion to $12 billion, be made of precast concrete, and rise 35 to 40 feet, or 50 feet, or higher. He’s said the wall doesn’t need to run the nearly 2,000 miles of the border, but half of that because of natural barriers.” http://www.politifact.com/truth-....

3. A physical wall: https://www.facebook.com/CSPAN/v...

4. “He called it a ‘beautiful and impenetrable’ barrier that would keep out criminals, drug dealers, and rapists sent by the Mexican government. Mexico, he said, would be made to pay the billions of dollars in construction costs … Mr [sic] Trump has said the wall would cover half the 2,000-mile border from Brownsville to San Diego, California, with natural barriers protecting the rest.” http://www.telegraph.co.uk/news/...

President-Elect Trump’s Promises:

1. “Donald J. Trump’s 10 Point Plan to Put America First … Begin working on an impenetrable physical wall on the southern border, on day one. Mexico will pay for the wall.” https://www.donaldjtrump.com/pol....

2. “Pay for the Wall Introduction: … Even a small increase in visa fees would pay for the wall. …” https://assets.donaldjtrump.com/...:

3. “One of the nation’s leading immigration hard-liners is working with Donald Trump’s presidential transition team. Kris Kobach, the Kansas secretary of state, told a Wichita-based television station he was consulting with Trump insiders on the future of U.S. immigration policy. … There’s no question the wall is going to get built,” Kobach told KWCH. “The only question is how quickly will it get done and who pays for it.” https://www.washingtonpost.com/n....

4. “Donald Trump plans to begin the process of constructing a wall on the southern border in March, sources familiar with the president-elect’s transition team told The Daily Caller News Foundation. The transition team is planning big spending negotiations with Congress at that time, which will include money for the wall — a platform on which Trump built his campaign for the presidency. He plans to make Mexico pay for the wall directly or indirectly by increasing fees on visas and border crossing cards, enforcing trade tariffs and taxing money transfers abroad. Trump has said the wall, which will be at least 35 to 50 feet high and made of pre-cast concrete, would cost anywhere from $8 billion to $12 billion. While about 650 miles of fencing already exist on parts of the 2,000 mile border with Mexico, Trump has promised to build a “real” wall that “actually looks good.” http://dailycaller.com/2016/11/1....

….

Despite the above, the latest news indicates that Trump is backtracking and will not be a physical wall, at least as originally proposed. See Yes, Trump will have broad power to crack down on immigration: “Extending the 650 miles of wall or fencing that currently exist would require congressional approval because of the billions of dollars that the project would cost. Trump told 60 Minutes that in ‘certain areas, a wall is more appropriate,’ but ‘there could be some fencing.’"

This has been pretty widely discussed. See: Trump reveals how he would force Mexico to pay for border wall, Sorry Donald Trump, Mexico Says It Will Not Pay for Border Wall

The problem, as the Washington Post discussed, is that it is “the feasibility of Drumpf’s plan is unclear both legally and politically, and it would test the bounds of a president’s executive powers in seeking to pressure another country.”

Something you have to consider about any policy Donald Trump proposes is that, as someone who has cultivated a willful and enthusiastic ignorance of how the business of government is done, he’s going to be pretty clueless about a lot of these sorts of things. He thinks “well, I’d be the president, so I can do what I want,” which, as it turns out, isn’t how the Founders set up the system.

But a couple of thoughts:

1.) Practically, it seems like you couldn’t both deport all of the illegal immigrants while at the same time relying on their wire transfers back to Mexico as leverage. You get to pick one or the other.

2.) Prohibiting wire transfers to Mexico by legal US residents, which he intends to do under the Patriot Act, involves a wildly expansive reading of the law:

“Drumpf is giving an extremely broad definition of this section of the Patriot Act and what it allows, and it’d surely be litigated,” said Stuart Anderson, executive director of the National Foundation for American Policy, a nonpartisan think tank in Virginia. “It would be a large expansion beyond what the text reads.”

So it is very unclear whether he would have the power to do the thing he’s going to say he wants to do, and the federal courts would almost certainly put the whole thing on hold until it had been legislated out.

3.) The core assumption of this argument is that, faced with the mistreatment of millions of its citizens and a threat to actively ruin its economy, the government of Mexico will cough up billions of dollars, presumably while quaking in fear. Why does Trump assume this? Because he has no foreign policy experience, and has yet to demonstrate even a minimal interest in it, or even an awareness of how clueless he is. What would your reaction be if a country made similar threats against the United States? Say China threatened to boycott the United States unless we stopped taxing their exports. Would we just immediately back down?

I think Vicente Fox has made it fairly clear what the reaction would be from the Mexican people: Former Mexican president slams Trump's 'stupid wall' - CNN Video

And the current president of Mexico has outright said that they won’t be paying for anything:

Mexican President Enrique Pena Nieto's administration said there's no truth to U.S. presidential candidate Donald Drumpf's assertion that the nation would pay for a wall along the border between the countries.

"Of course it's false," Eduardo Sanchez, Pena Nieto spokesman, said in a telephone interview with Bloomberg. "It reflects an enormous ignorance for what Mexico represents, and also the irresponsibility of the candidate who's saying it."

4.) With regards to the tariff, what you’re talking about here is a tax increase to hurt Mexicans. This is possibly the one combination of issues that would unite Republicans and Democrats in Congress.

5.) With regard to visa fees, this wall would realistically cost somewhere between $15 and $25 billion dollars, with a yearly maintenance cost of something like $700 million. How big of a dent do you think visa fees for Mexicans is going to put into that?

So the notion of Mexico paying for the border wall is ludicrous because Trump almost certainly can’t enact his plan to make them, that was poorly conceived and wouldn’t work anyway, and Mexico has confirmed that, indeed, they will not under any circumstances pay for a border wall. And the other methods proposed (visa fees, tariffs, etc.) wouldn’t come close to bringing in enough money.