Kangaroo Court

The kangaroo is an animal normally found in Australia, not Texas. However, it was Texas (or Mississippi) that came up with the term “kangaroo court,” meaning a court where the proceedings are a mere formality and the determination is pre-arranged.
 
The reason for the name is not clear, but a “kangaroo court” (cited in print from 1841) is one where the legal tradition is not solemnly applied.
   
 
Wikipedia: Kangaroo court
A kangaroo court or kangaroo trial, sometimes likened to a drumhead court-martial, refers to a sham legal proceeding or court. The colloquial phrase “kangaroo court” is used to describe judicial proceedings that, the speaker feels, deny due process rights in the name of expediency. Such rights include the right to summon witnesses, the right of cross-examination, the right not to incriminate oneself, the right not to be tried on secret evidence, the right to control one’s own defense, the right to exclude evidence that is improperly obtained, irrelevant or inherently inadmissible, e.g., hearsay, the right to exclude judges or jurors on the grounds of partiality or conflict of interest, and the right of appeal. The outcome of a trial by “kangaroo court” is essentially determined in advance, usually for the purpose of providing a conviction, either by going through the motions of manipulated procedure or by allowing no defense at all.
 
Etymology
The origin of the term is unknown. One theory suggests that the term comes from inside the early prison system of Australia (at the time, an English penal colony) where mock-courts were convened. Another theory suggests the term does not originate from Australia, the native continent of kangaroos. The oldest known usage stems from the California Gold Rush, with the first written reference (1853) in a Texas context (also mustang court), from the notion of proceeding “by leaps”, like the eponymous marsupial. It is possible that the phrase arose out of a combination of informal courts convened to deal with “claim jumpers”, such courts being named “kangaroo courts” by some of the many Australian participants in the Gold Rush, together with a bit of local word play. As many of the participants of the gold rushes had emigrated from Australia and were deeply unpopular, it is also believed that anti-Australian sentiment amongst more “local” participants resulted in predetermined outcomes against these Australian immigrants — hence, “kangaroo court”.
 
(Oxford English Dictionary)
kangaroo court orig. U.S., an improperly constituted court having no legal standing, e.g. one held by strikers, mutineers, prisoners, etc.
1853 ‘P. PAXTON’ Stray Yankee in Texas 205 By a unanimous vote, Judge G was elected to the bench and the ‘Mestang’ or ‘*Kangaroo Court’ regularly organized.
1895 Harper’s Mag. Apr. 718/2 The most interesting of these impromptu clubs is the one called in the vernacular the ‘Kangaroo Court’. It is found almost entirely in county jails.
     
24 August 1841, New Orleans (LA) Daily Picayune, pg. 2:
DON’T COMPREHEND.—The Concordia Intelligencer says “several loafers were lynched in Natchez last week upon various charges instituted by the Kangaroo court. The times grow warm; we can see another storm coming, not unlike that which prevailed in the days of the Murrel excitement. In Natchez, as in New Orleans, they are driving away all of the free negroes.” What is a Kangaroo court, neighbor?
   
12 January 1849, The Mississippian, letter to the editor, pg. 3, col 2:
Kosciusko, Miss., Dec. 1. 1848
(...)
On the evening succeeding the election, a meetimg was gotten up some what in imitation of a “Kangaroo Court,” for the purpose of trying three individuals, (not all of who had voted for Taylor,) on charges preferred, that one of them, H_____, is ever loudest to proclaim his democratic sentiments, but has never been known to vote for one of the party for any office, from President down.
 
27 July 1850, Spirit of the Times, pg. 269:
DRAFTS AT SIGHT ON THE SOUTH-WEST.
TERM-TIME IN THE BACKWOODS, AND A MESTANG COURT.
(...)
By unanimous vote, Judge G—, the fattest and funniest of the assembly—was elected to the bench, and the “Mestang” or “Kangaroo Court” regularly organized. Impossible as it would be for any one to convey to the reader a correct idea of the ludicrous and supremely ridiculous scene which ensued, I will yet attempt it.
(...)
THE INDICTMENT.
The Mestang Republic.
Kangaroo, to wit:—At the special court of Kangaroo county, begun and holden in the very extensive city of Kangaroo, to wit: One old shed for a court-house, two taverns such as they are, one blacksmith shop, with a post-office attachment, six groceries which we mean to leave as dry as an old maid’s lips, five banks (faro), and nothing else.
(...)
P. P.
N. Y. Literary World.
   
1 April 1851, Galveston (TX) Weekly News, , pg. 1, col. 4:
For the “News.”
BACKWOODS SCENES;
OR

BY SYLVESTER SILVERSIGHT
No. 1
A “New Comer” in a Tight Place.
(...)
Some time in the year 1831, or ‘32,...
(...)
“Ta’e him down?  Show him the varmint!  Yes, by G-d! we’ll introduce him tothe Kangaroo!” explained the gruff, but, at times jocose old Captain Leathershirt.
 
There was much of truth in the remarks of the old Captain, for, on the very next day—all things necessary forthe occasion having been arranged—the young gentleman was, in the most formal manner, shown the varmint—“introduced to the Kangaroo.” So that our readers may understand what was meant by the allusion to the Kangaroo, we will state that the San Felipeans had regularly organized a mock tribunal, called—a very uncouth appellation, by the bye—the “Supreme Kangaroo Court of San Felipe.” It was to this court that young Spindleshanks was introduced.
(...)
And they did “invistigate the matter,” to the utmost extent of the powers vested in the august Kangaroo Court.
   
18 June 1852, Galveston (TX) Weekly Journal, pg. 2, col. 1:
The Brazos Delta in speaking of the irregularity of the mails says:
 
We have had one regular mail in succession, within the last six weeks. It is understood that Judge Foster will hold a Kangaroo Court, to try the Houston mail driver for contempt of Judge Kangaroo the first time he brings through a regular New Orleans mail.”
 
Google Books
Birthright
By Clay Blount
Montgomery, AL: NewSouth Books
2004
Pg. 192:
The original Kangaroo had been located then, as now, near Glass Bayou just north of town. It had been established in the 1820s—shortly after Vicksburg’s emergence as a city of commerce—first as a whorehouse, then a saloon, and finally a gambler’s refuge.
 
Google Books
Black life on the Mississippi:
slaves, free blacks, and the western steamboat world
By Thomas C. Buchanan
Chapel Hill, NC: UNC Press
2004
Pg. 36:
In Vicksburg, slaves and free blacks met in the Kangaroo, a neighborhood named after its most famous brothel. Located just to the north of the business district, in a swampy dilapidated section of the city, the Kangaroo provided visiting workers a place to drink, fight, and gamble with an intensity that could not be controlled by the city’s planter and merchant elite.