Amid the national uproar over "religious freedom" legislation that critics say permits discrimination against gay people, there is also growing controversy over bills criticized for being "anti-transgender."

Lawmakers have proposed such bills in at least 12 states around the United States so far this year, ranging from Massachusetts to Oklahoma.

"The number of anti-transgender bills we are seeing in 2015 is much higher than we have seen in previous years," Alison Gill, a senior legislative counsel at LGBT civil-rights advocacy group Human Rights Campaign, told Mashable.

The dome of the Capitol stands in the background, as Stephen Saras of Atlanta holds a rainbow flag during a rally against a contentious "religious freedom" bill, on March 17, in Atlanta. Image: David Goldman/Associated Press

These bills have come in three main categories:

"Bathroom surveillance" legislation proposed in Massachusetts, Florida, Texas, Kentucky and Missouri seeks to prevent transgender people from using the bathroom of their choice.

Another type of bill proposed in South Dakota and Minnesota would prevent transgender students from playing in sports leagues based on their lived gender.

Legislators in Connecticut and South Carolina have proposed laws that would allow health insurance companies to deny services to transgender people.

"In a lot of ways, the anti-LGBT bills are a reaction based out of fear and misunderstandings of who transgender people are," Vincent Paolo Villano, communications director at the National Center for Transgender Equality, told Mashable.

Gill said the wave of "anti-transgender" legislation seems to be a response to "the gains we have seen in state and local non-discrimination policies that protect transgender people." Similarly, some believe the bills that are criticized for being anti-LGBT are part of the backlash against widening approval of gay marriage.

One such bill became law in Indiana, although a nationwide uproar prompted lawmakers to revise it. However, Villano believes that none of the bills marked as anti-transgender will likely make it that far.

“The good news," he said, "is that in any of the states where these bills are proposed, it’s not likely that any of them will pass.”