As we detailed yesterday, dozens of states are considering bills that attempt to nullify federal gun laws. One such bill became a law last month in Kansas. It exempts “Made in Kansas” guns from federal regulation and makes it a crime for federal agents to enforce federal law.

Attorney General Eric Holder recently wrote to Kansas Gov. Sam Brownback, saying the law is “unconstitutional,” and that the U.S. is prepared to sue Kansas to prevent the state from “interfering with the activities of federal officials.”

Now, Brownback has fired back.

In a letter to Holder yesterday, Brownback wrote: “The people of Kansas have clearly expressed their sovereign will. It is my hope that upon further review, you will see their right to do so.”

Local news reports have highlighted an estimate from Kansas’ attorney general that defending the new law in court could cost the state $225,000 over the next three years. Attorney General Derek Schmidt did not immediately return a request for comment.

“Our office has received more than 300 emails and calls in the last two days from Kansans and Americans from around the country thanking the governor for his response,” Brownback’s spokeswoman, Sherriene Jones-Sontag, wrote in an email. She also cited the many favorable comments on the governor’s Facebook page.

Kansas’ Secretary of State Kris Kobach, who helped draft the new law, also released a response to Holder’s letter. “As a former professor of constitutional law, I ensured that it was drafted to withstand any legal challenge,” he wrote.

“The Obama Administration has repeatedly violated the United States Constitution for the past four-and-a-half-years. That abuse cannot continue.”

Kobach told ProPublica that he does not consider Kansas’ law to be “nullification,” because the law only asserts that federal regulations do not apply to guns that are made in Kansas, and have never crossed the state’s borders.

“Nullification implies that you’re saying the whole federal law is wrong. That was the nullification of the 19th century. We’re not doing that…we’re acting with a scalpel.”

Kobach said he did not craft the legislation with the goal of provoking a legal battle. He said it’s also possible that the Justice Department will “decide that actually their legal position is not as clear as they thought” and back down.

Before the law can be challenged in court, he said, someone will have to be “directly injured” -- for instance, if the federal government decides to crack down on a Kansas gun manufacturer who decides to start making “Made in Kansas” guns without a federal license.

“We’re a long way from litigation at this point,” Kobach said.

Kansas’ Secretary of State Kris Kobach, who helped draft the new law, also released a response to Holder’s letter. “As a former professor of constitutional law, I ensured that it was drafted to withstand any legal challenge,” he wrote.

“The Obama Administration has repeatedly violated the United States Constitution for the past four-and-a-half-years. That abuse cannot continue.”

Kobach told ProPublica that he does not consider Kansas’ law to be “nullification,” because the law only asserts that federal regulations do not apply to guns that are made in Kansas, and have never crossed the state’s borders.

“Nullification implies that you’re saying the whole federal law is wrong. That was the nullification of the 19th century. We’re not doing that…we’re acting with a scalpel.”

Kobach said he did not craft the legislation with the goal of provoking a legal battle. He said it’s also possible that the Justice Department will “decide that actually their legal position is not as clear as they thought” and back down.

Before the law can be challenged in court, he said, someone will have to be “directly injured” -- for instance, if the federal government decides to crack down on a Kansas gun manufacturer who decides to start making “Made in Kansas” guns without a federal license.

“We’re a long way from litigation at this point,” Kobach said.

Similar bills nullifying federal gun laws are continuing to advance in at least three other states: Louisiana, Missouri, and Alabama. In Alaska, a bill exempting any gun possessed in Alaska from federal law has been approved by the state legislature and is awaiting action from Gov. Sean Parnell. Bills attacking federal gun laws have been introduced in at least 37 states this year.

Many of the bills have caveats. In Kansas, for example, the law specifies that state will not actually arrest federal agents who try to enforce gun regulations.

Bills in other states, including Montana, Wyoming, and Tennessee have attempted to go further. The approved version of Alaska’s bill removed a measure that would have allowed state law enforcement to arrest federal agents for trying to enforce gun laws.