Indiana's sex crime laws are very complex, because they describe different kinds of conduct and distinguish one kind of crime from another based on the age of the perpetrator and the age of the victim. In most of these, however, the perpetrator must be 18 or older to commit an offense, and many times, if the victim was older than 14 there is no crime. There are some crimes for victims between 14 and 16, but those still require the perpetrator to be at least 18. These statutes can be viewed at http://www.in.gov/legislative/ic/code/title35/ar42/ch4.html.
Most of these crimes look like a consensual sexual relationship between you at age 16 and the friend at age 20 would not be a crime. The problem you have is that you are still a minor and under the care of your parents. They have the right to make decisions for you, including when and with whom you go out. As for arresting the boyfriend if he shows up, there first has to be a crime. If there is no sexual activity, there should be no crime. If there is sexual activity, but you freely consent, there should be no crime. Please read the law carefully.
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I agree with Attorney Bowes answer and would reiterate that dating, in of itself, is not a crime and he cannot be legally arrested simply for being in a "relationship" with you.
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