Catholic colleges enforce ethical behavior and academic integrity similarly to most colleges. Though the specifics of what is considered ethical may vary from the perspective of a public or state college, the methods of enforcement are often alike.
Usually, what is considered ethical behavior is outlined in the student handbook. Some Catholic colleges may even require students to sign a pledge prior to their move-in. This pledge will often be a sort of agreement from the student to behave in a way that is acceptable, or ethical, as outlined by the college. These pledges, and the student handbook, will almost always have a section that explains academic integrity and outlines plagiarism, cheating, and dishonesty. By signing this pledge or accepting the terms of the student handbook, the student agrees to behave ethically, abide by the college's rules, and to uphold academic integrity.
Enforcement comes in the form of punishment. When unethical or dishonest behavior is committed by a student, there is something of a trial process. Usually, colleges will appoint a committee when a case is brought up. A professor (or whoever believes academic dishonesty has taken place) will present their evidence to the committee, and the student will be given the opportunity to plead their case or appeal a decision. If the student is found guilty, there are different degrees of punishment depending on the severity of their actions. In some cases, a failing grade is given, a class is forfeited, or a student is suspended. In more severe cases, some students can even be expelled.
Ethical behavior and academic integrity are of high value, especially at Catholic colleges as ethical behavior and honesty are emphasized in Catholic social teaching. This is a general explanation of a standard process to enforce ethical behavior and academic integrity. Keep in mind that not every college will have the exact same process or punishments. For more specific information about what sort of enforcement is in place and what standards are upheld for ethical behavior and academic integrity, check the website or speak with an admissions officer of the Catholic college(s) you are interested in.