Karen Fonseca was booked into Fort Bend county jail on Thursday. Seen above in her mugshot

The owner of a pickup truck featuring a huge decal on its back window saying 'f*** Trump' has been arrested.

Karen Fonseca was booked into Fort Bend county jail on Thursday after sheriffs discovered she had an outstanding warrant for fraud from August this year.

Sheriff Troy E Nehls had initially put out an appeal to find Fonseca with the idea of issuing her a citation for disorderly conduct over the offensive message.

But he later backed away from the idea after the district attorney warned the case would not meet the standard required to prosecute, and the American Civil Liberties Union stepped in to say the sign was constitutionally protected.

Nehls also received a personal backlash over the suggestion, with an assistant saying he had been sent threats against him and his family.

Trucking hell: This truck has been causing consternation in Texas - and now cops in Fort Bend County want to track down its owner on grounds of 'disorderly conduct'

Fonseca is the owner of a pickup truck featuring a huge decal on its back window saying 'f*** Trump '

Fonseca had said she would not remove the decal. She said she had been stopped by law officers, but that they have no grounds to issue a citation.

'It's not to cause hate or animosity,' the 46-year-old Fonseca told the Houston Chronicle. 'It's just our freedom of speech and we're exercising it.'

Free speech: Sheriff Troy E Nehls (pictured) says he may back off if the sticker is modified - but his threats are undermined by a Supreme Court constitutional ruling

She was booked into jail at 2pm on Thursday, records show, and has been granted bail set at $1,500.

The American Civil Liberties Union of Texas posted on Facebook that Fonseca’s message is protected speech and urged her to reach out to the organization.

The ACLU noted a 1971 U.S. Supreme Court case that overturned the conviction of a man for disturbing the peace for wearing a jacket with an expletive as part of an effort to protest the military draft and the Vietnam War.

In the case Cohen v California, the Supreme Court overturned a conviction against a 19-year-old Paul Robert Cohen for wearing a jacket reading 'F**k the draft' in a courthouse.

In a statement, Justice John Marshall Harlan II wrote: 'Absent a more particularized and compelling reason for its actions, the State may not, consistently with the First and Fourteenth Amendments, make the simple public display of this single four-letter expletive a criminal offense.'

He added: 'One man's vulgarity is another's lyric.'

Court in the act: As pointed out by the ACLU, in 1971 the Supreme Court overturned a man's conviction for wearing a 'F**k the draft' T-shirt in a courthouse, saying it was protected speech