Last month, President Obama returned from Cuba, where he took another step toward normalizing relations with the island nation. In his speech to the Cuban people, the president made the case that engagement is a more powerful agent of change than isolation, even where strong disagreements remain. With his visit, the president continued to chip away at the more-than-50-year U.S. trade embargo against Cuba.

Two days later, Ed Lee, the mayor of San Francisco, laid the foundation for a new embargo. He announced that San Francisco's city workers are banned indefinitely from traveling to North Carolina unless doing so is essential to public health and safety. The embargo is intended to protest North Carolina's new law prohibiting the state's local governments from enacting anti-discrimination rules that protect gay and transgender people and limiting transgender people to bathrooms that match the gender on their birth certificate. Since then, more cities and states, including Minnesota, have announced similar travel bans. Others will likely follow.

At the moment that our country is opening lines of communication and travel abroad, we are closing them within our own borders.

The bans apply only to official city or state travel, and it's unclear how often employees from these cities and states actually travel to North Carolina. But these policies are as much about message as effect. The problem is: It's the wrong message.

It's not that North Carolina's law is acceptable. It isn't. I was part of the legal team that brought an end to Oregon's constitutional ban on same-sex marriage, and discrimination based on gender or sexual orientation is harmful and inconsistent with our country's values. North Carolina's decision to thwart its own cities' efforts to prevent discrimination deserves condemnation.

And it's not that those who oppose North Carolina's law should sit on the sidelines; it's important that people and organizations take action when they see injustice, as we did in Oregon. The business, civic and political leaders who have spoken out against North Carolina's law, including by warning that they may not pursue future investments in the state, have sent a powerful message.

But should city and state government travel bans be part of the response? States are on the front lines of social and political issues. What would happen to our ability as a country to work through important issues if whenever a city or state perceived injustice in another state, it banned official travel there?

What if Ohio banned travel to Arizona because it deemed Arizona's policies toward immigrants inhumane? What if Texas barred state employees from traveling to Connecticut because it believed that Connecticut's gun control laws were unjust? What if Minnesota banned travel to Georgia to protest that state's use of capital punishment?

The presidential campaign is evidence enough that we live in a polarized environment. Do we need more lines in the sand, and fewer people talking and meeting with each other?

Not only do the travel bans potentially send us down a slippery slope, but also they are blunt instruments that could halt progress in other areas. Cities and states collaborate on many issues, from urban planning to public education. What would happen to this collaboration if their officials were not allowed to meet? Should city planners in Seattle be stopped from visiting a green building project in Charlotte? And what would happen to organizations that bring city and state officials together, such as the U.S. Conference of Mayors? Would they splinter into factions, with their events held at approved locations for each constituency?

Even setting aside the restriction on travel, these bans undermine collaboration. They erect walls between public employees, placing entire states on one side or the other, with no exception for areas where their views and work are aligned.

For city and state governments wanting to take action, here's an alternative. Rather than ban travel, do the opposite. Take a page from Obama's book and organize a trip to North Carolina. Bring along a coalition of political, business and civic leaders who can present their views and experiences on inclusiveness for gay and transgender people to residents and public officials there, engaging them in a direct dialogue.

Perhaps by humanizing the issue and opening rather than closing lines of communication, we could remove the fear and misunderstanding underlying North Carolina's new law and plant seeds for more genuine and long-lasting change.

Nathan Christensen is an adjunct professor at Lewis & Clark Law School in Portland, Ore. He wrote this article for the Washington Post.