Although I am not licensed in Texas, as a general rule, it is better to decline the field sobriety tests. However, also as a general rule, it is better to submit to testing at the station. Most states make a refusal to test a crime. Even where it is not a crime, the license ramifications can be far more significant than taking a test and failing
In Colorado, a DUI suspect is allowed to decline to take the field sobriety tests as well as the hand-held, portable breath test. If the officer has probably cause to arrest, then the suspect is required to cooperate with testing of their blood or breath. The penalty for refusal is a one year loss of driving privileges for a first refusal and the DA may suggest to the jury that the refusal is evidence of a guilty conscience.
Many jurisdictions follow the same rule.
Best of luck.
If you are pulled over in the middle of the day with perfect weather conditions, you subsist on a diet of bread and water, you take no medications, and you are a perfect physical specimen, then taking the FST and submitting a breath sample is a no-brainer. Otherwise, you do so at your peril.
FSTs are a subjective measure of intoxication. Ostensibly, there is science that supports their use as an accurate, objective measure of intoxication. But the shoulder of a busy highway at night is not the appropriate environment to apply that science. Regardless, any tests you take -- as well as anything you say to the officer -- can be used against you in court.
Submitting a breath sample makes police, prosecutors, and sometimes jurors happy, because it reduces a measure of your intoxication to a neat little number. If that neat little number is above another neat little number, then you're intoxicated and guilty. If that neat little number is below another neat little number, then maybe your breath doesn't say your intoxicated and guilty, but that extra step you took while performing the FST sure does. At any rate, submitting a breath sample places the question of your guilt or innocence in the hands of a machine and numerous technicians who may or may not follow the standard operating procedure for chain of custody and who may or may not operate the machine appropriately.
If you submit to FSTs or give a breath sample, you essentially are providing evidence to the state. In Texas, you do NOT have to provide this evidence against yourself. But if you refuse to provide breath or blood (there is no penalty for refusing to perform the FSTs), you do face consequences.
Refusing to provide breath or blood can result in your losing your license for 180 days. If you are polite enough to provide evidence against yourself, and your breath or blood tests for a blood alcohol concentration of 0.08 or greater, than you only lose your license for 90 days. You do get a chance to argue to keep your license, but the standard at the hearing is very low, and successes are rare.
Losing your drivers license for three or six months is, to put it mildly, a complete bummer. But a conviction for DWI is a swift kick in the pants that will hurt for years. Not only will you face the possibility of probation or even jail time (there is no deferred adjudication for DWI in Texas), but you will also have to pay the Department of Public Safety $1,000 per year to keep your license (for your first offense). For three years. But before you have the privilege of paying that surcharge, you will lose your license for 90 days to one year.
In the end, the choice is up to you. Watch the pen, walk in a straight line, blow in the straw, lose your license for three months, and give the state a pile of evidence to use against you. Or stand your ground, keep your breath and blood to yourself, and give yourself a fighting chance against the charges. It's your call.
This answer is provided for educational purposes in response to this particular question, and does not create an attorney-client relationship. For legal advice regarding your individual situation, please consult with a local attorney.
As a Board Certified Criminal Specialist in Texas, I tell all of my clients and friends, NEVER take any test. NEVER take any test. NEVER take any test. If the officer asks you to take the test to "make sure you're OK to drive", he has already decided you are going to jail. Don't give them any evidence to convict you. Provide the nice policeman with your driver's license and insurance and then let them know that you have complied with their requests and would like to be on your way. If they refuse to allow you to leave then you should tell them that you feel that you have been arrested because you are no longer free to leave and you would like to call your attorney. Don't talk to the officer. Don't answer the officer's questions. Don't make small talk about anything with the officer. DO NOT take any breath test and repeat every time you are asked anything, "I want my lawyer."