On June 23, Australian journalist Peter Greste and two of his Al Jazeera colleagues were sentenced to jail in Egypt for, according to the court, supporting the Muslim Brotherhood and spreading false news.

"The devil guided them to use journalism and direct it toward activities against this nation," the court said in a statement explaining its verdict.

The international media was swift in condemning the decision.

In public and private discussion, ideas were shared on how Greste could best be assisted - how Egypt, with its unconscionable ruling, could be made to see the error of its ways.

For travel journalists, this meant considering a boycott. Writers wondered if we should cease producing articles about "why there is no better time to visit the Middle East" and those pharaoh statues recently unveiled in Luxor. Was it wrong to promote travel to a country that had just incarcerated a respected Australian journalist on ludicrous charges?

Many thought boycotting was appropriate. Others, however, saw the whole discourse as largely pointless. A boycott would achieve nothing, they argued; and besides, if you are willing to sanction Egypt for its abysmal treatment of journalists, what about China, Malaysia and Vietnam?

Peter Singer, the Australian moral philosopher based at Princeton, offered me the following opinion: "I can understand Australians boycotting Egypt at present because of the jailing of Peter Greste, or, perhaps more serious[ly], the outrageous number of death sentences pronounced on protesters.

"A boycott may be one way of getting some leverage on these things when nothing else seems to work. But I don't think that there is a general obligation to boycott all countries that are doing something unethical."

Singer said there had to be a public campaign to achieve effective change, "which one can support by a boycott".

But, in the absence of public campaigns for most offending countries, how does a conscientious traveller know where to draw the line?

Tours to North Korea and Congo are now readily accessible.

What makes one country ethically acceptable and another appropriate to put on the no-fly list?

Sometimes the answer is relatively straightforward. The US government's embargo of Cuba began in 1960; most Americans are still banned from visiting the communist stronghold.

In 1999, Aung San Suu Kyi, the beloved leader of democracy in Myanmar, advised international travellers not to come to her country by calling tourism "a form of moral support" for the military junta.

In both of these cases, the ethical dilemma was taken up publicly, with clear directives passed down from higher powers.

In most instances, the terrain is far more ambiguous, though, and decisions rest on individuals.

Israel is a case in point: a person's willingness to travel to Tel Aviv in times of peace depends on their attitude towards the so-called "Palestinian Question" and Israeli occupation of the West Bank. For the longest time, I have refused to travel to Israel under any circumstances; many of my friends have no such objection.

While they tour the sights of Jerusalem, I find myself wondering if my stance means I should not also skip over Turkey (occupying Northern Cyprus), and Russia (parts of Ukraine, Moldova, and Georgia). One way to consider the problem is to separate out the levels of culpability.

Calls for boycotts are rarely generalised: they arise in response to specific ethical violations. It is important to ask who, in particular, is responsible for these violations. China as a nation oppresses Tibet; the only Canadians clubbing seals are fishermen in Newfoundland and Quebec.

Boycotting both of these countries to the same extent means confusing an appropriate sense of scale.

Instead, by examining perceived injustices closely, boycotts can be implemented where they are most effective. I have no problem travelling through the American south, for example, but I would walk out of any restaurant that exhibited signs of racial segregation.

When they work, boycotts can cause embarrassment, financial pressure, and, in particularly effective cases, policy changes and collective soul-searching.

"The reality is that the mere awareness of a boycott causes the target constituency and its supporters to attend more to criticism of their government's or companies' policies," writes Michael Marx, of Corporate Ethics International, in an article for the Business Ethics Network. "[I]nevitably they become more aware of the legitimacy of the criticism."

This rationale of shaming people into penitence came up earlier this year with widespread calls to boycott the Dorchester Collection, a string of luxury properties owned by Sultan Hassanal Bolkiah, who is responsible for implementing an outrageously strict Sharia penal code in Brunei.

In 2006, Brunei's constitution was altered to affirm that Bolkiah "can do no wrong in either his personal or any official capacity".

Scores of influential luminaries begged to differ, including Richard Branson and Ellen DeGeneres.

Anna Wintour even relocated her usual base during Paris Fashion Week in open protest.

"If we don't tell him he's wrong, no one else will," explained Matthew Fleischer in the Los Angeles Times.

Not everyone is convinced by these kinds of efforts, though.

In May, Russell Crowe took to Twitter to voice his discontent: "I don't agree with the boycotting of Dorchester Collection hotels," he wrote. "It only hurts the hard-working staff who I consider friends."

Setting aside the question of whether hospitality jobs are really commensurate with women being stoned to death for adultery, Crowe's objection raises an important point.

Travel boycotts are rarely free of collateral damage. Say the travel industry does punish Egypt because of Peter Greste, causing tourism to plummet even further than it already has in the current climate of constant revolution.

And say this punishment does (however improbable) have the intended effect of intimidating the government into reconsidering its verdict. In the meantime, the people absorbing the greatest impact from our blockade are street vendors and family-run businesses that rely on the influx of visitors to stay alive.

Another thing to consider about travel boycotts is their inherent power dynamic - the elevated ethical position that you, as boycotter, place yourself in compared with the group or country you elect to boycott as unethical. A good example is Sri Lanka, which many Australians have long looked down upon for its human rights abuses against the Tamil minority.

But recently the Australian government was caught trying to return Tamil asylum seekers to the Sri Lankan navy; Volker Turk, from the office of the United Nations High Commissioner for Refugees, has questioned whether Australia "is in line with international law and standards".

Suddenly, the ethical high ground looks a little rocky. At what point does a foreign traveller decide to boycott Australia because they look down on our refugee policy?

The idea is alarming, and endlessly arguable, but it illustrates how complicated ethical judgments can actually be in travel. While it is tempting to divide the world map into opposing sides of goodies (New Zealand) and baddies (North Korea), realpolitik is far more challenging.

Some places are genuinely indefensible and should be avoided at all costs - Angola, for instance, for its rampant human trafficking and Uganda for its draconian anti-homosexual policies - while other destinations require more thought.

Aung San Suu Kyi reversed her opposition to Myanmar tourism in 2009, but a rigorous traveller will still research their hotel choices, trying to avoid anything with direct ties to the military dictatorship; and, after arriving, that traveller will still spend money in stalls and villages where government oversight is less intensive, funnelling kyats to the people who need them most.

I recently spoke to a respected Australian writer who has been working in travel for several decades. Always attentive to the ethical implications of his many assignments, he once turned down a lucrative gig to South Africa because he opposed its policy of apartheid.

In the early 1990s, when France began testing nuclear bombs in the South Pacific, this writer campaigned in The Sydney Morning Herald for a travel boycott. But the number of Australians who visited France actually increased during the period.

The truth is, people will go wherever they want to go.

Travel boycotts are only recommendations for collective resistance; they are rarely enforceable. Ethics come down to personal intuition, and it is the traveller's responsibility to gather all the facts before they buy a plane ticket to Jamaica or book a hotel suite at Le Meurice.

As a result, everybody's no-fly list is probably different.

My own list changes all the time, depending on the news. Uganda currently sits at the very top, tied with the likes of Sudan and Somalia and Russia.

The reason for this was summed up in a radio exchange between Stephen Fry and Simon Lokodo, a former Catholic priest who is now Uganda's minister for "ethics and integrity", whatever that means.

"It is not permissible in Uganda for single-sex relationship," Lokodo told Fry. "Finished. And if you are advocating that, I'm sorry I will treat you as a destructor of Uganda's ideologies."

That means he will sentence you to life imprisonment under the "Anti-Homosexuality Act", which originally called for the death penalty for gays until international aid donors reacted with outrage and threatened to withdraw their aid funding.

My own boycott against Uganda might seem small by comparison, but surely every little bit counts. What better way can a traveller change the world than through the decisions they make in this trillion-dollar industry?

ABOUT THE WRITER Lance Richardson is a New York-based Australian writer interested in culture and the less-visited places. He is currently working on a book about wolves.