Can an employer write you up for taking rest room breaks?

Technically, yes, an employer can write up an employee for violating any policy, even a stupid one like this one.  Fifteen minutes to use the restroom per week sounds like this supervisor has a defective dial tone.  You are not without some remedies though.  First, pull out your employee handbook.... if you don't have one, get it from HR.  If your handbook has the five minute per day rule in it, you need to complain to HR (or to your boss's boss) that this supervisor is violating company policy.  Many call centers are a part of larger organizations.  Many handbooks will also have a 1-800 confidential "hotline" for reporting abuses just like this one.  They usually have these policies to encourage "open communication" which they hope will discourage labor union activity.    A second option is to contact OSHA.  Breaks are not automatically required, but they can be a part of a safe working environment if employees become ill because they cannot "relieve" themselve appropriately.  OHSA doesn't like to get involved in these issues, but it's free, and it's worth a shot to get them to come out and inpsect your company.  If they are this stingy on breaktime, they may be stingy on more serious safety issues and equipment. A third option may be to file a discrimination complaint.  If this rule is only applied to your one group-- but not to other groups-- and your group is comprised of a mainly members of a protected group (like mainly minorities or mainly women), then the policy would seem directed at creating a hostile work environment for this one group.  You could then file a complaint with the EEOC or the Texas Human Rights Commission.