| Passive/tacit/silent consent | Presuming that the persons object if they do not consent. | Unnecessary or resource-consuming to have express consent. |
| Implicit consent/inferred consent | Consent is given implicitly in or can be inferred from an action. For example, a person consenting to cancer surgery implicitly consents to being cut in with a scalpel. | Unnecessary to have express consent. |
| Presumed consent | Consent under the presumption that people (in general) would have consented to the treatment or research were they able to consent. | Unnecessary or impossible to have express consent. |
| Hypothetical consent | Consent under the presumption that a person would have consented to the treatment or research were she or he able to consent. | Unnecessary or impossible to have express consent. |
| Future/deferred consent | Postponing the consent procedure. | Impossible to have express consent. |
| Broad consent/general consent/generic consent | Consenting to a wide (broadly specified) range of options. | Difficult to predict future options or practical challenges with renewed consent. |
| Blanket consent/open consent | Consent to an unlimited range of options. | Impractical to renew consent. |