Twitter and Square CEO Jack Dorsey Kimberly White/Getty Images for Vanity Fair Silicon Valley leaders believe the government has overstepped its bounds, once again.

In the shadow of the very public Apple-FBI fight over encryption, tech titans have been coming together to lend a voice to another issue: discriminatory travel restrictions.

In an open letter published today, more than 30 industry leaders, including Twitter CEO Jack Dorsey, Mark Cuban, and venture capitalist Michael Moritz, voiced their disagreement with a law passed in late December.

Under the Visa Waiver program, the US used to allow travelers from 38 countries, largely in Europe, to visit the United States for a short period without needing a visa. This allowed employees of Silicon Valley giants like Google or Facebook from other countries to freely visit their headquarters. Customers looking to buy American tech products could easily fly to the US for a demo, argues Ali Partovi, a noted angel investor and one of the supporters of the letter.

These travel freedoms was cut short in the wake of the terrorist attacks in Paris and San Bernardino, and was intended to block European jihadists from coming to the US.

But Silicon Valley leaders believe the new law goes too far.

"In the balancing act between fighting terrorism and upholding American liberties, these provisions go too far," the group wrote.

In the balancing act between fighting terrorism and upholding American liberties, these provisions go too far.

The amended law bars people who traveled to Syria, Iraq, Iran, or Sudan in the last five years to enter without a visa. Most controversially, those who are dual citizens of Syria, Iraq, Iran, or Sudan are also forbidden from entering the country without documentation.

This becomes especially tricky given the countries' views on what qualifies as a citizen. Iran, for example, counts children of male Iranian nationals, regardless of their place of birth, and their spouses as citizens of the country, according to a UNICEF report. British citizens of Iranian heritage who have never set foot in the country would have to apply for a visa just because of their birth parents, Partovi explained.

"Discriminating based on national heritage is inconsistent with American values. In effect, certain provisions of the new law require visas for Europeans and other citizens with Iranian, Sudanese, Syrian, or Iraqi heritage," the group wrote. "We protest this just as vigorously as if Congress had mandated special travel papers for citizens based on their faith or the color of their skin."

Business leaders are also concerned about the economic impact.

Some tech employees and customers have already been blocked from entering the country because they didn't realize their parents' nationality played a role in their travel plans, Partovi told Business Insider.

"Restricting travel handicaps American companies from being as competitive they want to be in the international marketplace," Partovi said.

Beyond just voicing concerns, the Silicon Valley heavyweights are also throwing their power (and in some cases, likely money and influence) behind the Equal Protection in Travel Act (H.R.4380/S.2499) that would remove the restrictive dual nationality clause. The group released its letter Tuesday on a Change.Org to gain signatures for a petition as a show of support.

A new bipartisan bill introduced in January would eliminate the dual nationality clause, but would not lift the restrictions on those who traveled to other countries.

Here's the full letter and list of supporters: