Texas Civil Practice and Remedies Code - CIV PRAC & REM § 10.001. Signing of Pleadings and Motions

(1) the pleading or motion is not being presented for any improper purpose, including to harass or to cause unnecessary delay or needless increase in the cost of litigation;

(2) each claim, defense, or other legal contention in the pleading or motion is warranted by existing law or by a nonfrivolous argument for the extension, modification, or reversal of existing law or the establishment of new law;

(3) each allegation or other factual contention in the pleading or motion has evidentiary support or, for a specifically identified allegation or factual contention, is likely to have evidentiary support after a reasonable opportunity for further investigation or discovery;  and

(4) each denial in the pleading or motion of a factual contention is warranted on the evidence or, for a specifically identified denial, is reasonably based on a lack of information or belief.