The right to consent is a fundamental human right. Whether to medical intervention or physical contact, establishing consent is a key way of communicating our respect for others. It's also essential to establishing a person's autonomy and agency. We'll talk about specifics later, but to do that we need to think about what consent really means.
Elements of Consent
For the purposes of our conversation, consent requires 4 elements:
Capacity to make the decision.
Understanding what is included in the consent
Ability to voluntarily grant consent, without coercion or duress
Ability to communicate consent
Capacity
This is really simple. To consent to something, you need to be mentally capable of making the decision. For adults, we pretty much assume that everyone is capable of consenting to just about anything unless they are intellectually unable to understand what's going on. That could either be from a medical issue like dementia or due to impairment from a drug or alcohol. Unless that's the case, adults can consent to whatever. But if an adult is unable to consent, there are 2 options. Either another adult can be appointed to represent that person and decide consent if it's in their best interests, or there's no consent. Period.
Children aren't that different. Technically, children aren't old enough to consent to anything. In the US, the age of consent for most things is18. For sexual activity, that age can vary by state, but is usually at least 14. Since children can't consent to anything, an adult makes that decision for them. Those are usually parents though obviously there are other kinds of guardians that have the same rights.
But for kids, there's another thing called assent. Assent is the agreement of the child to participate. And children as young as 3 have a right to assent. As long as the child is able to understand what's going on at an age-appropriate level, a child has the right to refuse as long as they're not risking their own life, limb, or eyesight.
Information
This probably seems obvious. But to consent, you have to understand what you're consenting to. In medicine, this includes the risks, benefits, and alternatives to a procedure. In personal life, for example, it means that you have a right to limit the extent of sexual contact with someone. "Yes" doesn't mean "yes to everything."
Voluntary Consent
Consent also has to be voluntary. So, you can't be forced to consent. And you can't be pressured to consent to something. If you agree under pressure, you didn't actually consent. Pressure comes in many forms. It can be direct statements from another person telling you to agree. It can be social pressure, like disapproving looks from your doctor or spouse. It can be threats or reminders of how your decision will hurt others. It can even be as subtle as an understanding of the social pressures if you refuse. But whatever it is, any pressure to consent makes the consent invalid.
Communication
It's great to be capable of consent, but the ability to communicate that consent is a whole other issue. Bottom line: if someone can't communicate consent, it's not consent. This is particularly true for those with conditions that limit communication, like situational mutism, or for those who speak a foreign language. If proper communication lines are not established, consent doesn't exist. And by the way, the responsibility to assure communication is adequate belongs to the person seeking consent.